author
35Instructables1,557,653Views11,022CommentsUK LincolnshireJoined August 30th, 2006
Retired technology teacher - 2 kids, I have an Hons deg in Design and Technology - 28 years as Computer systems engineer Trained as Electronics engineer in the Royal Air Force

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  • rickharris commented on hobbit590's forum topic In over my head - pH automation7 weeks ago

    Ok I take your point.Lets see if my experience is any use to you.1. Your going to need to start by writing a really detailed User Requirement Specification (URS) for what your client wants - detailed down to the last $ of costing, the sizes, the expected outcomes - this is YOUR bible - if you can respond totally to that specification your client will be most happy and the project will be a success.2. your going to take that User Requirement specification and write your response A functional Specification (FS). this will detail HOW to do the job, what is required for each element, costings and any other information needed to do the job - eg. your going to need to locate and get the specification for a suitable sensor to do what the URS wants. That will probably (but not limited to) be i...

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    Ok I take your point.Lets see if my experience is any use to you.1. Your going to need to start by writing a really detailed User Requirement Specification (URS) for what your client wants - detailed down to the last $ of costing, the sizes, the expected outcomes - this is YOUR bible - if you can respond totally to that specification your client will be most happy and the project will be a success.2. your going to take that User Requirement specification and write your response A functional Specification (FS). this will detail HOW to do the job, what is required for each element, costings and any other information needed to do the job - eg. your going to need to locate and get the specification for a suitable sensor to do what the URS wants. That will probably (but not limited to) be interfaced with a microprocessor. You need to identify the relevant inputs and outputs your going to need so you know how big (or small ) the microprocessor needs to be. 2. You need to detail to the point of identifying ranges of accuracy etc, Materials, the fluids your dealing with and any other restrictions you can possibly think of that apply to the project. (this isn't easy - I used to do this as a consultant for big money but the more thorough you do this the easier the project will be.)Note:The sensors your going to buy and MUCH of what you do after that depends a lot on what they need.to be continued...

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  • rickharris commented on hobbit590's forum topic In over my head - pH automation7 weeks ago

    https://www.google.com/search?q=Automatic+PH+contr...Do the research

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  • More details needed: chill down to what?do you need physical presence?Partner to do what? electrical, mechanical, Software?

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  • rickharris commented on zikkij's forum topic Code for website7 weeks ago

    That web site is created as a blog so anything you fancy really. i use Blogger from Google - works for me.http://nz-2015rah.blogspot.com/

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  • You don't say WHY you need to do this - but your highest energy density is going to be a lead acid car type battery (that's why they use them in cars)Couple that with a suitable sized inverter and you have a semi portable power source.HOWEVER I would approach this in a different way and build a PC suitable for battery use. having used the raspberry Pi I found it to be fairly easy with LOTS of support.https://www.instructables.com/howto/PI+PC/

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  • rickharris commented on AdvanŽ's forum topic Stairs redesign8 weeks ago

    Use safety glass or Plastic. Safer but lets light through.Or use a net mesh of some kind.

    1. Stair gate at top and bottom Preventing accidents is easier than dealing with them2. Box in the open side but use safety glass so you keep the open view.3. Fill in the gap between stairs.4 they are really steep I think in the UK they wouldn't meet building code - i guess nothing to be done about that.

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  • Not that I know about. But your PC probably has an HDMI input on it.

    For me I would play the HDMI signal through my PC, Use Audacity (free) to record it. Then play the second one and record it. Use audacity to mix both sound captures and output as you want.

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  • rickharris commented on potofgold's forum topic 4 wheeled Quad-Cycle!2 months ago

    https://www.instructables.com/howto/velomobile/

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  • It beats me. many of the most frequent contributors to his "forum" have extensive software development experience, it's free why not use it.

    I could vote for that

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  • The Questions page is STILL prey to listing posts that are years old. This can't be a serious problem. just make the page more obvious.

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  • 1. Does it work2 No - there is something missing3 Yes - fine carry on.The definition of QUALITY in a product is that it does what the end user wants.There may be many more components in a commercial product for various reasons, legal or practical - However something that works to your satisfaction is a success on any level.

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  • rickharris commented on Simon-does's forum topic Vending machine2 months ago

    You just might get more interest if you put more details in. like where are you in our wide world, What are your skills, What skills are you looking for, WHY should anyone help out. Why is this project going to be very exciting (or as is possible is it just that you need a vending machine and thought you might get some free help?

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  • rickharris commented on elami123's forum topic Make a CNC with Camera2 months ago

    IF you have the hardware and software skills to complete the project I can see 3 ways to go about this.1. Use a fairly standard line follower type circuit (lots of examples on the web)2. Raster scan the image looking for black using a camera with a very small field of view - in fact you could do this with a simple light sensor. When you read a black point pulse the laser to cut.3. As DU says capture the image and vectorise it reduce the contrast until only the black lines show. Then convert into Gcode for cutting.For me I wouldn't do any of this at all - I would build the CNC system and slave it mechanically or electrically to a pointer, run the pointer over the parts of the image you want to cut - Job done. Something like the way a copy router works.

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  • it's a Prusa I3 my son owns it.

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  • Building a flight simulator, making some silver jewellery for friends in New Zealand, Improving 3D CAD skills now I have access to a 3 D printer.

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  • rickharris commented on LoloN1's forum topic Robotics Aspirant 3 months ago

    https://www.instructables.com/class/Robots-Class/https://www.instructables.com/id/Lets-Program-a-PI...https://www.instructables.com/id/Reading-Sensors-With-a-Microprocessor/https://www.instructables.com/howto/arduino+robot/I don't know your starting skill level but Robots suggests microprocessors. When you crack using them the hardware is fairly straightforward.http://solarbotics.net/it isn't totally necessary to use a microprocessor, So called BEAM robots use standard electronic components to achieve amazing results. https://www.lego.com/en-gb/mindstormsis always an optionhttps://mindsetsonline.co.uk/product-category/robo...has ideas and lots of materials if you in the UK.

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  • How to Ask a Question in Instructables.

    Ken:1. This instructable is to show you HOW to ask questions (in the community area oft the forum)2. However Unless you have a very serious reason to run the bulbs in series don't, they will be half brightness and if 1 blows they both go out.Run the 2nd bulb in parallel the first. see diagramDisclaimer: I can't see what you have done and so am talking principles here not practicalI am not a certified electricianI don't know where you are so you need to make sure your work is to local code.Anything you do you do at your own risk.Click on diagram to open

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  • rickharris commented on seamster's forum topic What's on your tool wish-list?3 months ago

    I thought a bit more - My CAD skills are fairly high, 2 D and 3D using Sketchup so a CNC router, A 3D printer, + the consumables necessary to run them.

    You can get microprocessor based oscilloscopes very cheaply now, they connect to your PC for a display.https://www.rapidonline.com/voltcraft-dso-2020-usb...https://www.picaxestore.com/index.php/en_gb/catalo...even cheaper. £14 !!

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  • rickharris commented on seamster's forum topic What's on your tool wish-list?3 months ago

    Laser cutter

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  • rickharris commented on randofo's forum topic Old How-To Books3 months ago

    https://books.google.co.uk/books?id=vOhIAAAAMAAJ&p...Popular mechanics from 1950 Adverts are interesting.

    Google books is an excellent source for old bookshttps://books.google.co.uk/books?id=vOhIAAAAMAAJ&p...is a book of 500 mechanical mechanisms, many forgotten about today.

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  • rickharris commented on Downunder35m's forum topic VR gaming parties anyone?3 months ago

    A win on the lottery here allowed me to buy an Oculus system for my Birthday this year. My intended use is as a headset for a flight simulator (in progress). 1. I was astonished by how immersive it is.2. I was disappointed to find i could see the pixels in the head set.3. If your prone to motion sickness (i am) then this perhaps either isn't the technology for you or your going to take a long time to get acclimatised 4. You really really need a fairly large dedicated place for it. Setting up, putting away is a pain.

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  • Even more confusion. The search algorithm is even picking those posts with the latest update. I reposted in my original comment about old and new posts getting mixed up and lo and behold it stays at the bottom of the list, isn't that curious.

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  • rickharris commented on wdemarche's forum topic DIY Scuba Tank (breath underwater)4 months ago

    To breath underwater you need a DEMAND regulator. Not just something to lower the presure.

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  • For me although the making and problem solving is enjoyable I still only make things that others want or I want. That way I need to get to the end.breaking a project down into small sections with defined outcomes also helps a lot. that way you can see and touch each milestone as they are finished.A project isn't a monolith - one big chunck of work it's a lot of minor triaumphs that when fitted together make something wonderful.

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  • FLIR Thermal imaginghttps://www.amazon.co.uk/prettygood7-Infrared-Prof...

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  • https://electronics.stackexchange.com/questions/23...Found by google search - click on image for full size.

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  • Your soldering leaves much to be desired. You need to check that you don't have any bridges across the tracks. Double, triple check your circuit is assembled correctly.

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  • If you don't have much building experience this is going to be complicated.HOWEVER: Your best bet in my opinion is to source an electric scooter strip it down and fit the parts to the bike.Ebay may be your best source if you want to buy separate bits.For the most part you don't need complex speed controllers a simple on off button will surfice if you get the motor and gearing correct.

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  • To some degree I appreciate what you say.However as I recall the real reason questions dies off is that the site made it harder to find the question option. Since then it has been made harder and harder. So fewer questions.I thought the main thrust of the site after show and tell was to educate and promote the maker ethos.Most of the "old hands" at answering questions have left, frustrated by the difficulty in finding and answering. Shame.It might just be that a section for offering technical help with your projects should be prominent and perhaps headed "HELP WITH YOUR PROJECT" Not relatively hidden and headed "TOPIC"Mmmm - As someone who understands the value of being able to ask questions of a wiser and more experienced head I would hope this will be r...

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    To some degree I appreciate what you say.However as I recall the real reason questions dies off is that the site made it harder to find the question option. Since then it has been made harder and harder. So fewer questions.I thought the main thrust of the site after show and tell was to educate and promote the maker ethos.Most of the "old hands" at answering questions have left, frustrated by the difficulty in finding and answering. Shame.It might just be that a section for offering technical help with your projects should be prominent and perhaps headed "HELP WITH YOUR PROJECT" Not relatively hidden and headed "TOPIC"Mmmm - As someone who understands the value of being able to ask questions of a wiser and more experienced head I would hope this will be resolved in the near future.

    Just as a by the by the sort isn't even working as sorting recent replieshttps://www.instructables.com/topics/Vertical-Axis...for example hasn't had a reply in the past 4 months and yet is only 2 posts below this one I wrot a few days ago. Something wrong there.

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  • Will this be changed as suggested to put newest topics at the top?You end up either having to read every publishing date or answering questions that will never be read again by the original author.My understanding of this section was that it was there to share the expertise of the collective "brains" of instructables, may i say some very highly qualified and experienced brains at that, to help makers with their projects.An answer 10 years down the road isn't helping anyone.

    Possibly a setting, I'll try the mobile app, Oh no they abandoned that as well!!A voice crying in the wilderness, but I try.

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  • Drying anything requires that the water molecules are excited to make them 'jump' away from the material, a breeze then blows those molecules away.We often add heat because this energises the water molecules to' jump' higher and makes them easier to blow away.Something like the image attached (click for bigger view) would work.BUT for cheapness omit the dehumidifier and just vent the moist air outside replacing it with air flow from the house.A modest heat is all that is required, IF you put wet clothes over a heat source then you MUST put a shield between the clothes and that heat source + sensible protection against overheating. NEVER leave such an apparatus unattended.

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  • Glad to be a help."Check out linear actuators" as I said - 90 % of the problem is knowing where to look. Good luck with the development

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  • rickharris commented on Worby10's forum topic Circuit design4 months ago

    You don't say when you want the light to go off - If you want it to go off when you flip the switch again then all you are doing is reversing the switch operation.There has to be more to the specification than this. Tell us.

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  • I assume you want a saddle pillar mounted ar, I don't think it matters much as long as the trailer arm is free to pivot so the trailer can follow as it wants, the trailor wheels must be parallel and parellel to the center line.

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  • Whilst we are discussing this you will find it hard to get the platform to stop abruptly at the ends of travel. Unless you allow a distance to getup to speed and slow down you may not get the 1 inch of constant speed you need.The commercial way to do this is to implement a PID loop (look it up - You tube has some videos.) so that as the platform nears the end it starts to ramp down the speed coming to a stop exactly on the mark every time.this may or may not be an issue for you but I suf=ggest you will need as a minimum an end limit switch and probably some kind of soft buffer if you don't use a PID loop.

    On a sewing machine that does exactly this there is no mechanical guide the tread just naturally sits side by side, all you need is a gap between the thread exit and the spoolhttps://www.google.co.uk/search?q=rethreadding+a+b...

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  • I missed out a picture of this done directly with a belt.You would need to find or make a motor run at a suitable speed

    OK a length of 6 mm all thread rod has a 1 mm pitch, that is for each turn of the rod the nut travels 1 mm, so 25mm in an inch.You need to get 25 Rev per sec = 1500 RPMA lot of small DC motors will do 3000 RPM or more, the load will be very light.This should work for you.Yes the toothed belt is as you say - see image.Amazon have a choice because of people making 3D printers.Of course you can size your pully to give you higher or lower RPM at the rod.You can click on the images to see it bigger.Check out Linear actuators. both DIY and commercial.To drive the motor both ways you will need an H bridge. If your using an Arduinohttps://www.instructables.com/id/DC-Motors-Part-1-...https://www.instructables.com/id/H-Bridge-for-Dumm...Or a DPDT switch if you want to try it manually initiallyHa...

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    OK a length of 6 mm all thread rod has a 1 mm pitch, that is for each turn of the rod the nut travels 1 mm, so 25mm in an inch.You need to get 25 Rev per sec = 1500 RPMA lot of small DC motors will do 3000 RPM or more, the load will be very light.This should work for you.Yes the toothed belt is as you say - see image.Amazon have a choice because of people making 3D printers.Of course you can size your pully to give you higher or lower RPM at the rod.You can click on the images to see it bigger.Check out Linear actuators. both DIY and commercial.To drive the motor both ways you will need an H bridge. If your using an Arduinohttps://www.instructables.com/id/DC-Motors-Part-1-...https://www.instructables.com/id/H-Bridge-for-Dumm...Or a DPDT switch if you want to try it manually initiallyHave fun

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  • It depends on how fast you need the platform to move. If relatively slowly then a DC motor driving a length of threaded rod with a nut on it attached to the platform will do the trick and is easy to speed control with PWM( Pulse width modulation).Faster movement then i would go to a Toothed belt and a stepper motor, this is going to need some research on your part to understand how to drive it , but there is a LOT of information on the web.You might get away with a dc motor and step down gear box, say from a cordless electric drill or screw driver. This can drive a toothed belt.

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  • Taking into consideration my comments above I am not inclined to help you build such a device - Sorry. It isn't something your going to use for the benefit of anyone other than yourself and maybe to the detriment of others.I repeatThe energy required would be considerable, IF you don't know how your not likely to be safe with such potentials.

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  • 1. EMP = DEAD not disabled. Thats DEAD forever. You may not want this2. Your neighbours would hunt you down assuming this were possible.3. The energy required would be considerable, IF you don't know how your not likely to be safe with such potentials.

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  • rickharris commented on BoomGuy's forum topic Rotary Tool neck thread size4 months ago

    The generic dremel I have is of German origin and has an M8 fine thread

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  • How to Ask a Question in Instructables.

    1 start at the opening page. (This is the page you start at ie the log in page (see my image)2. Click Community3. Click New Topic4. Enter your question5. Hope for a helpful answer.There isn't any reason not to use a 24 to 12 volt converter, make sure it can handle the current. However I assume your using lead Acid batteries (car type batteries) - I doubt personally you will deplete the charge on 1 to the stage they wont charge properly.In principle it is possible to get an unbalanced system, SLA's are very robust. HOWEVER if your battery bank is Lipo based then things are different.

    1. Welcome to Instructables the biggest show and tell site there is.2. I am pleased you read through my intro to how to ask a question.3. So that more experts will see your question I suggest though that you go to The Intro page (the first one you see when you enter Instructables, Select COMMUNITY, Select New Topic and cut and paste your question in there - You will get more views and potentially more answers that way. Only i as the author get notifications from this instructable.4. Obviously I am not at your house so Only have a vague understanding of what you trying to do - thanks though for the explanation, - if your using 2 x 12 volt battery you can tap off 12 volts from one battery and the 24 volts from both batteries See diagram

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  • rickharris commented on redlethe's forum topic How to heat a tent- safely?5 months ago

    DON'T burn charcoal or any solid fuel inside a tent without a working flue.People have dies from Carbon monoxide by putting a disposable BBQ in the tent because it was raining.Gas isn't much better unless you make a gas fires secondary air heater. ie the gas heats air which heats your tent.Our Marquees are electrically heated if necessary,When Camping I wear more clothes and have a 4 season sleeping bag, if your cold get in it.

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  • rickharris commented on minus273degrees's forum topic making methanol5 months ago

    https://www.youtube.com/results?search_query=Makin...

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  • For many years my father used a cut throat razor. (I never had the courage), He sharpened it every time on a leather strop before use. Never saw him put any abrasive on the strop though.He was a steam engineer all his life and a tool that wasn't sharp was the devil incarnate to him. I think my Mother has kittens every time I went into the shed to help him do something.However he taught me respect for sharp and heavy things, how to sharpen them and how to use them. Result, I became an electronics engineer!!

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  • I have seen on good old You tube people using an MDF wheel as well, a bit more sturdy I suppose but for light work the cardbaord works fine.

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  • Best advice for sharpening any tool is do little but do it often. I polish my knife on a cardboard wheel on my grinder, a little jewellers rouge give an excellent edge.

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  • rickharris commented on nedwired's forum topic Archives5 months ago

    The instructables search feature works quite well. it uses google to search the site.

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  • A scissor jack Effectively a linear screw actuator can lift much ore than 2 tonnes with a humans feeble input. The linear thrust from your screw will be very high.

    https://12vactuators.com/how-to-calculate-linear-a...https://cdn2.hubspot.net/hubfs/4316198/Downloads/t...

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  • In the UK bar keepers Friend is very similiar by the sound of it, To feel it is just like old fashioned Jif powder cleanser now sadly degraded into a cream cleaner, no where near as good.For polishing small jewellery I made a barrel tumble polisher from an old Film developing can and a few lego wheels. Works great with mild abrasives to polish to a high standard and gets into all the nooks etc. i often use cork as a polish carrier.Images from Amazon and Cooksongold.

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  • There are many stencil fonts available for freehttps://www.google.co.uk/search?q=stencil+fonts+fr...Other than that you can take any font, Fill with white or transparent depending on your software capability and add the links to prevent the cut out area falling out - example below I produce in my CAD programe

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  • rickharris commented on guyfrom7up's instructable Free Energy6 months ago
    Free Energy

    Got me there.

    Technically it is the ground state of a quantum mechanical system is its lowest-energy state; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state. Not to be confused with electrical energy.

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  • rickharris commented on bilesl's forum topic Right glue for the job6 months ago

    https://www.thistothat.com/

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  • rickharris commented on DUMB8's forum topic Cheap ideas6 months ago

    If it's really big make a garden seat.If smaller a coffee table.

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  • rickharris commented on DUMB8's forum topic Cheap ideas6 months ago

    https://www.google.co.uk/search?q=wire+sculpture&s...

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  • rickharris commented on Wario_Bros's forum topic Hi, I'm New :)6 months ago

    I realise your a newcomer but if you want a satisfactory answer you have to engage in the conversation!

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  • You will need to do some tests to ascertain the drag coefficient of the board and you and efficiency of the EDF unit. Then the calculation is basic maths - You need to overcome the drag + enough thrust to give you the speed you need. For a flying aircraft this is generally less thrust than the weight of the air frame because drag is, (generally), low. If you were talking about a model than for performance your looking at 200 watts per pound minimum (more in real world for EDF) So weigh yourself and the board and work it out.Your going to find it hard to locate an EDF big enough.A paraglider motor is around 120-500 cc and outputs to a 2/3 foot propeller. to push you along your going to be in the same range.

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  • rickharris commented on Wario_Bros's forum topic Hi, I'm New :)6 months ago

    Although not specifically Arduino the principles apply to all micros.https://www.instructables.com/id/Lets-Program-a-PI...https://www.instructables.com/id/Reading-Sensors-W...The Arduino home site has lots of help. or Ask Google.

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  • rickharris commented on bravoechonovember1's forum topic Collaboration experiment6 months ago

    Rather pointless exercise Chinese whispers with a practical bent.Why not use the undoubted expertest here and really do some good for someone?

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  • rickharris commented on rav527's forum topic Rotating multi-layer Face scupture 6 months ago

    If I were to do this I think I would try to use a single motor at the bottom driving a common shaft through each segment of the sculpture. The segments would be driven or not by a clutch mechanism at each segment. This probably takes up less space than a motor at each segment.You are severely hampered by wanting to make a small version, this means you won't have the space to put the mechanism. You would need to have some mechanism that indicated when the segment was in it's "home" position.Driving in different directions calls for sme extra gearing. this could be simple rubber wheel rubbing on the inside of the core.

    It strikes me that if your prepared to compromise a little on the looks you could mount the drive system outside the sculpture as in the diagram. this would be easier at a small size. If light rubber bands would do for the drive belts and model motors for the drive. Click on diagram for full size.

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  • rickharris commented on bravoechonovember1's forum topic Collaboration experiment6 months ago

    Exactly what are you thinking of collaborating on?Examples:I am currently planning to build a flight simulator based around X plane 11 with motion platforme. I want to emulate the control panel as well as the instruments without having to buy expensive USB instrument clusters. I have some ideas about how to go about this but there seems to be little already on line that doesn't use bought instruments. The sim has to be mobile!Ex 2. My local primary school is interested in some machine learning for the slower pupils so they can go through a task several times in different ways to help their understanding. Ideally this should have some kind of success reward system built in to encourage the pupils and should be usable with minimum teacher input so the teacher can get on with the lessons w...

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    Exactly what are you thinking of collaborating on?Examples:I am currently planning to build a flight simulator based around X plane 11 with motion platforme. I want to emulate the control panel as well as the instruments without having to buy expensive USB instrument clusters. I have some ideas about how to go about this but there seems to be little already on line that doesn't use bought instruments. The sim has to be mobile!Ex 2. My local primary school is interested in some machine learning for the slower pupils so they can go through a task several times in different ways to help their understanding. Ideally this should have some kind of success reward system built in to encourage the pupils and should be usable with minimum teacher input so the teacher can get on with the lessons with the others. It can't be expensive. It has to be child safe and should include hands on practical operations to reinforce the learning.

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  • Not possible. To get the flux density you would need many turns of copper wire that will take up much more room.https://www.electronics-tutorials.ws/electromagnet...

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  • rickharris commented on bravoechonovember1's forum topic Collaboration experiment6 months ago

    Without a goal there isn't any imperative. Unless the project collaboration is not over something physical ie a design concept only. e.g.1 Who owns the finished project2. Who funds it3. what skills are you thinking about?

    Ok, in that case much more detail needed before I, or anyone I guess will commit time and effort.

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  • rickharris commented on bravoechonovember1's forum topic Collaboration experiment6 months ago

    What project are you thinking of. Suggest something for a school, or community center, or someone dissadvantagsd . I am interested

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  • rickharris commented on Phil B's forum topic Rescue a defunct phone charger6 months ago

    Fair enough. Anything is safe if you respect it and understand what - might - happen.IMHO you sound safe :-). Alas many people arn't!.

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  • rickharris commented on rav527's forum topic Rotating multi-layer Face scupture 6 months ago

    This will b very difficult to do:1.You don't know how it works (only what it does)2. It will be costly3 You have identified a number of points - search there are instructables for making 3 d scanners. - There are many online sites that can, for a price, print such an object from a suitable file.- Cutting it up neatly will be a big issue. - Rotation and control will require you start learning to use and programme microcontrollers.It's a big big job.

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  • rickharris commented on Phil B's forum topic Rescue a defunct phone charger6 months ago

    Electrically speaking this is a poor idea. Mains electricity and open circuit - even covered in hot glue isn't good.Especially for an item that costs very little to buy. Indeed if you go to the reception of a hotel they will have dozens of chargers under the counter for free that guests have left behind.However well done for fixing it.

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  • rickharris commented on ambientvoid's forum topic Lipo battery cut off7 months ago

    1. Your Lipo should already have a protection circuit on it or on the PCB for charge and discharge protection.2. Change the alarm output for a flashing LED.3. Pu the audio alarm in a tin can to amplify the sound.

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  • I guess the software skill set isn't very good because some of those liks contain pointers as to how it was done.A little research around micro mouse programming would give you much more.I can't see anyone doing this for nothing.Also the question isn't specific so we don't know how much he has done (or not) Has he a platform yet?

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  • rickharris commented on DabuHackker's forum topic WheatStone bridge7 months ago

    The current (electrons) will flow from negative to positive. and, assuming all the resistors are the same value will go equally across the top and bottom of the bridge. A to B to C and A to D to C. this is a balanced circuit.If one resistor changes value then more or less current will flow from A to C through that changed resistor. This unbalances the cct and current will try to flow through the low resistance meter one way or the other thus making the meter effectively reads the change in resistance.(Click on diagram to see it bigger)https://www.electronics-tutorials.ws/blog/wheatsto...

    I should add that the current flows through the meter because that will be the lower resistance pathway.

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  • You need to study the micro mouse maze runner concept. This is just what they do.http://ais.informatik.uni-freiburg.de/teaching/ws1...https://www.robotshop.com/letsmakerobots/tags/mapp...http://www.ipb.uni-bonn.de/robot-mapping/https://blog.hackster.io/build-a-3d-room-mapping-r...

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  • I would imagine getting the flow of material to be continuous. You might get better results by first making the bottle into a filament.Alternatively you could use some kind of glue gun type of system where material in a chamber is compressed, melted and squeezed from a nozzle your still working with a limited amount of material though.You also need to limit the material to the same kind of plastic so it all melts at the same temperature.

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  • rickharris commented on Bill Haas's forum topic Slip ring7 months ago

    depending on the power passed through the slip rings and good old fashioned VCR tape head containg a supurb set of slip rings and bearings that could be repurposed.

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