Make a Mini Guitar amplifier! This simple practice amp is easy to build and fun to play! Use it with your favorite speaker cab, or DIY your own. The best mini amp is the one you make!
This simple electronics project uses a LM386 amplifier chip with a real wood head and speaker cabinet. Mine uses recycled paper headphone speakers.
Parts required:
LM386 chip, dip 8 style
Socket, dip 8 style
10 Ohm resistor, 1/2 watt rating
220uf capacitor, electrolytic 16v
100uf capacitor, electrolytic 16v
.047 capacitor, film type, 16v (or higher depending on what's available)
.01 capacitor, film type, 16v(or higher)
Perf-style electronic project board
9v battery plug
1/4" input/output jack (x 2)
25 ohm Rheostat(optional volume control pad)
Wire
Solder
Soldering iron.
Magic marker
Begin by drawing the layout on a peice of paper. This will help you understand the parts involved and how you'll be attaching them together. This is especially helpful for polarity of things like electrolytic capacitors. Also think about how your chip socket relates to the rest of your parts and wiring.
After you have a good idea of how you will "layout" your project, transfer your drawing onto your perf board with magic marker on the top of the board.
Start building the amp by placing your empty chip socket into the perf board. Bend a few pins to keep it in place.
Next, add the 10 ohm resistor, 220uf capactitor and 100uf capacitor. Bend those pins to keep the parts in place. Add the .047 cap and the .01 cap and bend the pins.
Double check your schematic and layout. Is everything in the correct place? Capacitor polarity ok?
Good, now you can solder your parts in place.
Now you need to wire up your creation.
For power, you are going to make a voltage "Rail" and a ground "Bus"
Voltage Rail:
Using a peice of thin wire (i prefer solid core here) make the connection between where your red 9 volt battery plug wire:
1. attaches to the board
2. to pin 6 of the chip AND
3. to the "+" side of your 220uf capacitor.
The wire will probably look like an "L" and you should solder it at all 3 points.
Ground Bus:
Wire the ground bus by connecting socket pins 3 and 4 with solder or a tiny wire jumper.
1. Solder a bare wire from socket pin 3/4 to the end of the board where your .047 cap and your 100uf cap (negative -) terminate. This wire will probaly look like a large "L" or a large "T".
2. Run the wire neatly along a row of empty perf-holes since you will be adding more "ground wires" to the bus.
3. Add your battery connector if you haven't already. (+) to pin 6, (-) to ground bus.
Add your input jack, positive to the open side of the .01 film cap(which ultimately connects to socket pin 2. The ground wire goes to the perf board ground bus.
Add your output jack, Positive attaches to the (-) side of the 220uf electrolytic cap.
The ground wire attaches to the perf board ground bus.
If you want a Rheostat volume control, wire it in place of the output jack(middle leg), then wire the output jack to either open leg of the rheostat as shown in the video.
If you want a High gain amp, make a jumper from a small peice of wire and install it between socket pins 1 and 8. That will set gain from "20" to "200". The video shows the high gain setting.
Install this into your favorite cabinet, or altoids tin, or candy package, or....
This amp will drive virtually any speaker cabinet.
Here's another way to make a mini amp: Mini Printed Amp
Buy an amp here:
https://amzn.to/2ZxKAbV MARSHALL
https://amzn.to/2RhMg4V DANELECTRO
(purchasing through affiliate links will result in me earning a commission)
Enjoy your new amp!
Hi great little project. I assume that the 0.047 and 0.01 caps are uF ?
ReplyDeleteHi, i tried to build this amp but the sound is terrible, I might have connected something wrong, I don't know. the sound right now is like basically like a thunder, with a lot bass, also you can't really say which note u are playing because of the thunder thing... Also i am new to this. I don't know if it's correct but I considered the 0.047 and the 0.01 capacitors are uF, one of them is like a little white plastic box and the other one is a normal dark red film capacitor. Please, anything will help so much. Thank you.
ReplyDeleteHey Oscar, try disconnecting pins 1 and 8, that's the gain. That might help with the overpowering thunder/volume while you debug the circuit.
DeleteIf there's CRACKLING that sounds like thunder, that makes me think its a connection issue somewhere between the guitar and the amplifier chip.
Also, Triple check against the schematic that every single connection is correct. This is sometimes the difficult part because things can seem upside down when you're looking at them.
make sure also that your Electrolytic capacitor is Polarized properly (+ or - going to the correct places.
If you want to post a video to Youtube(or elsewhere) I can see more clearly what the problem is.
If you do this, try to give a clear shot of both sides of the board.
Let me know how it's going after you've tried these steps!
-Frank
Hello, thank you so much for helping! It works perfectly now, a capacitor was not places properly. It has really good sound. If you put the guitar volume low it sounds clean and if you put it high it sounds distorsioned. I love it!
DeleteIs there any way i can add a picture or something of it on this post?
Thank you so much, it is an amazing project.
Okay! I will send it to you :D
DeleteIf i were to put a (fake) reverb circuit in there would it go before the lm386? Would there need to be a buffer or preamp before the reverb?
ReplyDeleteI would put it before the lm386, and I would use a preamp before the reverb.
DeleteIn many ways the lm386 amp is just like any other amp, so it can be treated as such. Some of the chip variants are 4 watts @ 8 ohms. Most reverb circuits wouldn't appreciate that kind of signal.
Preamp(or buffer)> Reverb > LM386 amp > Speaker should get you what you want.
Brilliant, cheers G
DeleteActually what would be a clean/transparent sounding pre amp circuit youd recommend before the reverb?
DeleteThis little amp, or something like it should work fine:
Deletehttp://runoffgroove.com/omega.html
Thanks and one last thing; looking for speaker to put in, are there any specs I need to look out for i.e. nominal rated power? Does it matter?
DeleteI'd go with 8 ohm and between 1 and 5 watts.
DeleteIf you want a speaker and a jack out in one piece is there a recommended way they should be wired? Which one first? Does it matter? thanks
ReplyDeleteYes, Wire the speaker and the jack in series with each other.
ReplyDeleteThe jack would come first. The jack should be a shorting jack type. The tip(positive) would go to the switch. With no plug inserted, the jack shorts between the amp and the speaker. When the jack is inserted it breaks the circuit and the "other" speaker is in line with the amp.
Check out this thread for a diagram:
ReplyDeletehttps://www.tdpri.com/threads/adding-an-external-speaker-out-jack-to-my-combo.143104/
You've been an amazing help mate thank you. Iv'e hooked up the jack like in the diagram however it still doesn't cut the speaker, this is jack im using for output:
ReplyDeletehttps://www.thomann.de/gb/goeldo_j0019_stereoklinkenbuchse.htm
Also there's sometimes crazy oscillation when I try plug in the jack, although that does stop when i touch the input jack s could be a just grounding issue? I am using 9v power supply not battery. And the project is on breadboard at the moment in case any of that helps
Hmm, did you purchase a "shorting" type jack? It has a special spring which closes or opens a circuit, depending on whether or not it's being used. I don't think the jack you sent to me is a shorting type jack. That might also explain your grounding or hum issue. Shorting jack looks like this:
Deletehttps://www.stewmac.com/electronics/amps/amplifier-parts/jacks-and-plugs/switchcraft-shorting-jack.html?utm_source=google&utm_medium=shopping&utm_campaign=2020-12-gp&gclid=Cj0KCQiAzZL-BRDnARIsAPCJs72LqtnoYJYkK49-SjNMz_NIyTloPCyiyrPK7ZfvQlWQaj1AZCG3IpoaAvGWEALw_wcB
can i connect a headphone on the output jack?Will it burn ?
ReplyDeleteHeadphone on the output jack is fine!
Delete