Hello everyone this is my first tutorial on instructables!
Over a year ago I decided to make my own AMP, it had to be able to play music from your phone to big speakers. It had to be small, but still capable of playingloud music. I also wanted to be able to ajust the volume. It had to look nice and be easy to use too.
I'm from the netherlands so if there are any grammatical mistakes in this tutorial sorry for that.
I didn't plan on making a turorial so there might be a lot of pics missing, if you don't understand a step let me know in the comments and I'll explain it better and help you.
Later I improved my AMP and added the possibility to use it with car power (12 volts jack).
Materials and tools:
- 7 watts amp (bought on german website Conrad, click here to view, for 10 Euros
- Soldering device
- Soldering wire
- Wood (I used a small wooden box i found)
- 3,5mm male jack to 3,5mm male jack cable, to connect to your phone
- Switch to turn it on/off
- 50k logarithmic potentiometer (volume button)
- handsaw or other wood cutting device
- wire clip thing (the round thing on the side where you stick the speaker wires in)
- 230 to 12 volts adapter (Europe) in America it's probably different but you should be able to buy a suitable adapter at your local electronics store.
- a female 3,5mm jack for the AMP
- a female jack for the 12 volt powed input (own choice what kind of jack, as long as it has a positive and negative pole)
- a male jack for the 12 volts adapter, usually your 12 volt adapter will have a jack, but it might not fit into your female jack, so i changed it.
- a button to put on the potentiometer
Step 1: The Box
First used a wooden box where the amp would fit in. The round hole on the side is for the speaker wires to come in, There will be a thing to stick them in. I drilled holes in the front so it would not overheat. It's better to make these on top but for my design the front was better.
I painted the box and painted front plate later. Be sure to apply multiple layers of paint, so it looks nice. Check the description of your paint to see how long you need to wait before applying a new layer. I used white because it's clear and nice.
Step 2: The AMP
after the paint is dry you can put the round thing in the side. I don't know how that thing is called but it has a red and black thing you pull and release to keep your R and L wire from your speaker stuck in it. you can also use bolts and squeeze them so the wires dont come off. If the speaker you are planning to use uses jacks to power them, just buy the female version of that jack.
The AMP needed to be soldered, unfortunately I didn't take pictures of that. But there are a lot of soldering tutorials online. I used a 7 Watts AMP powered by 12 volts.
The 12 volt signal first goes to the on/off switch, then to the AMP. the amp also has a positive and negative output for the speakers, you solder these to the round thing in the side. always check the polarity!
The input from the 3,5mm female jack (linked to your phone) will connect to the potentiometer to offer the posibility to adjust the volume. Ask your local electronics store for a 50K ohm potentiometer (NOT LINEAR!), tell them it's to adjust music volume, they will know what you need. They will also tell you how to solder it. If they don't, just ask them.
I added an optional red LED to show if the AMP is on or off, to do that you simply solder an LED to a resistor and add it parallel to the power supply of the AMP. What resistor you need depends on what LED and power supply you use. There are a lot of websites to calculate the LED you need. I used a 1,8 volts red LED, and my power supply was 12 volts. you also need to know the power draw from your LED (in mA), if you don't know what your LED has just use 20mA, that's the most common, also what I had. Based on this I needed a 520ohm resistor.
Solder your resistor to the LED and solder the thing you made to the power after the switch, once again, watch the polarity.
Step 3: Put It All Together
Once everything is working and everything is soldered in place, you can put the switches, potentiometers and everything else in the hole you drilled and cut. Then you can glue it together and you are done! You can also chose to use nails or bolts to keep everything in place, but I prefer glue since you see it less.
If you can't get your AMP to work let me know what you are struggling with and I'll help you.
Thanks for reading and enjoy your AMP :)