Comment

Comment by Scavanged Sound (Pete) on June 14, 2016 at 2:35am

Simon I've had some success with a variant of this circuit. Based on the Little Gem. I use a witchcraft input jack. So when you plug in the guitar the circuit is complete. Un plug and it shuts down. No battery drain and no switch required. Although adding a switch can increase the cool factor. I'll post some pics of my circuit and wiring lay out.

Comment by Simon Cartlidge on May 28, 2016 at 8:24pm

Thanks guys, from the sounds of it I've wired it up right, my SW1 is a dpdt on-on so I've ordered an on-off-on off eBay. (I haven't got a day off to go and get a replacement this week and there's no electronics shop in town) I've ordered a new LM386 too just in case there's a fault in mine so I think I'm going to strip it all down and try again. If there's no mistakes in the schematic I can't imagine what the problem could be.

Comment by Mickey Sadler on May 28, 2016 at 2:19pm

The down pointing larger triangles should be connected together, this is the "common" or ground.

The up pointing smaller triangles should be connected together, this is the "power" or +9v to the circuit.

The switch SW1 should be a double pole double throw center off switch (also called a on-off-on switch). As drawn when in the up position, power is turned on and the audio output is connected to the earphone jack. When in the down position, power is turned on and the audio output is connected to the speaker. In the center or off position, power is turned off and the audio output is not connected.

The 10k pot R2 is the volume control.

Give it a try like that and let us know if it works.

Comment by Paul Craig on May 28, 2016 at 9:35am

That bottom right of the schematic shows a switch for what looks like choice of battery or walwart and should have a middle leg diverting power to the circuit at the top going to led, caps and pin 6. 

We need to see what Simon has done on the board though to troubleshoot his board.

Comment by Graham Wedepohl on May 28, 2016 at 8:41am

OK looking at that circuit, the LED will always come on. To make it switch off add a simple spst switch from the + on the battery to SW1.

R2 pot is the volume control.

Comment by Paul Craig on May 28, 2016 at 7:42am

I though it meant up too til I saw the grounded circuits looked the same.

A good pic of the top and bottom would be helpful.

Comment by Simon Cartlidge on May 28, 2016 at 7:40am

I took the little upwards arrows as matching up so put the positive from the battery to pin 6. My board probably looks even more confusing as I have a lot of things off board, I'll try show my setup.

Comment by Paul Craig on May 28, 2016 at 6:51am

Looking at the schematic is a little confusing. I t has the battery in part down by the amps output to speaker and show the pin 6 to go to ground(little triangle) when the battery + should be going to that pin. Should be a on off switch right after the battery before the led Circuit.

Can you take a pic of your circuit board?

Comment by Simon Cartlidge on May 28, 2016 at 6:33am

Hi folks, 

Just after a little advice. I've just built my first amp using this schematic I found online and it doesn't seem to be working. When I plug the battery in the LED lights up straight away (there doesn't seem to be any way to turn the amp off) but I'm getting absolutely nothing through the speaker or the headphone jack. I had tried adding a volume pot between J1 and C1 to start with too (J1 tip to one leg of the pot, C1 to the middle and J1 ground to the other) with not having a volume in my cbgs but even taking that out of the circuit still nothing. 

Can anyone see any major problems or come up with a reason why I'm not getting any joy?

Thanks.

Comment by Simon Cartlidge on May 16, 2016 at 12:41pm

Thanks Paul, I might pick up a couple of different values and try them out, see what the sound's like.

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