(DIY) Class D Amplifier/booster

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changed my mind, AAA's suck, use 9v..

Also

qldnuggytom said:
Just use a B&Z booster I got that on my F1a4 going to an adapter cable to the earplug works great
Click to expand...

$195 for an LM386 from the mid 1980s I think not..
B&Z like most other Amplifiers has about $30 in parts in it

I'd rather spend $27 on parts, and build it myself... Because i can.
 
im using the treasure mate II.
I would recommend these highly. well built also. and 9V.

i must agree with the above. if you have the know how.
i would make one also if i new what they where before i brought it.
i should of done some research first.
 
I built my own using jcar components, amplifier module, on / switch, case, 2 x 3.5 jacks for external speakers, runs on 9v battery, only need low volume due to amplifier. Frequency range very good. Works well. Still on first battery.
 
Need to bump an old thread.

I have been working on getting this amp going recently and am having some problems. I have built it exactly the same as the original
parts list and the wiring diagram.

I have a problem with interference.

With a gme spk07 speaker plugged straight into the detector, it works fine, nice and clear.

When i plug in the amplifier module and a different gme spk07 wired to suit, i get an interference humm which is quite loud.
I can hear the signal in the background, but there is some interference that it masking the audio.

I have tried the amplifier board with a 50k pot for volume originally, though there might have been a problem with the amp board,
so i ordered more and got some of the boards with the volume pot on board.

Same problem.

Im sure im doing something stupid. But ive got no idea what.

Can someone confirm the wiring for the plug that goes into the gpx5000 battery? im using a stereo plug.

Thanks heaps.
 
The wiring diagram for standalone speaker use so the battery amp trips is on page 13 of the manual. Don't wire your amp like this.

B&Z boosters, attached leads (older models), detachable leads (newer models) & sockets are wired mono. The supplied speakers are wired as per page 13 of the manual & work both with the B&Z booster + as standalone speaker tripping the batteries internal amp.
From all reports (I'm not electronics savvy) the B&Z is just a commercially available class D amplifier so maybe mono wiring is the go & try your speaker that works fine when plugged straight into the detector battery?
 
Neo__04 said:
Need to bump an old thread.

I have been working on getting this amp going recently and am having some problems. I have built it exactly the same as the original
parts list and the wiring diagram.

I have a problem with interference.

With a gme spk07 speaker plugged straight into the detector, it works fine, nice and clear.

When i plug in the amplifier module and a different gme spk07 wired to suit, i get an interference humm which is quite loud.
I can hear the signal in the background, but there is some interference that it masking the audio.

I have tried the amplifier board with a 50k pot for volume originally, though there might have been a problem with the amp board,
so i ordered more and got some of the boards with the volume pot on board.

Same problem.

Im sure im doing something stupid. But ive got no idea what.

Can someone confirm the wiring for the plug that goes into the gpx5000 battery? im using a stereo plug.

Thanks heaps.
Click to expand...

Just wondering if you ever found a solution to this, as I am having the same problem with the buzz.
Thanks
Andrew...
 
The wiring is a standard stereo configuration but if you are using a mono amp, the connect the shield to the outer ground as well as the ring of the plug and the active core to the tip of the plug.

Those amp module do have a bit of background hiss though.
 
Thanks again,
But I not sure that is the issue. I am getting a similar loud buzz similar to what Neo__04 was getting. It is like to tones. Almost sounds high pitched like a siren, with the tone of the detector underneath it. If I power the amp without the detector switched on, I can hear a perfectly clean his only when I have it turned up fully. As soon as the detector is turned on, I get the high pitched buzz as well as the detector. Both about the same volume....
I have another board coming soon, so I will try that incase this board is faulty.
Thanks.
 
ok bear in mind that being a digital amp, the input ground and output ground can not be connected together. They dont have a common ground rail like analog ic's. Also you may need a decoupling capacitor on the input to stop any dc. Without seeing the wiring diagram its a bit hard to know how you have it hooked up.
 
That is what I think is wrong as well Steelpat.
There is a feedback loop here some where. :)
Generally I would hang a Cap off the input line(s)
anyway. :) :)
These small amps only amplify noise. They have no filtering on board.
Or very minimal.
Also twisting your lead paths is a good idea as well. :Y:
 
Tathradj said:
That is what I think is wrong as well Steelpat.
There is a feedback loop here some where. :)
Generally I would hang a Cap off the input line(s)
anyway. :) :)
These small amps only amplify noise. They have no filtering on board.
Or very minimal.
Also twisting your lead paths is a good idea as well. :Y:
Click to expand...

Yeah its a bit of a trap with those digital modules. Lots of people connect the - output to the ground or connect the speaker between the + output and gnd. Its a big no no with those modules. Our latest enhancer/booster has filtering and virtually no detectable background hiss/noise.

I shall join as a sponsor in the next few days so I can show what just we released on the market.
 
I am thinking that it may be the board.
The power side is totally separate from the audio side. I am using the same parts as listed in the OP apart from the amplifier board which I got from Jaycar.
and is the arduino-compatible-2-x-3w-amplifier-module/p/XC4448
Power is supplied from the detector battery into the booster box with pass through to the SD2000. 6v goes to the regulator and 4.99v after the regulator which is supplied to the module. I have a 10k pot on the input side for the volume, and out put straight into the 6.5mm Stereo Socket for the speaker.
I can't find any shorts, and the negative side of the power doesn't come into contact with the ground of the audio side.
I will try the new board when it arrives to see if that makes a difference.
Thanks,
Andrew...
 
Because you are using the common ground of power to detector and to the amplifier you may need to isolate the output of detector to the input of the amp. You may find that the 'ground' of the headphone output on detector is lifted from the power ground.

Easiest way to tell is use a 9v battery just to power amp module and see how that works.
 
Hi Steelpat,
Yes, you are 100% correct. I hooked up a 9v battery to the input side of the regulator and the tone is gone. Works perfectly.
So now I need to work out the best way to isolate the ground to the amp.
Thanks again for all your help with this.
Andrew...
 
Hi again, Just wondering Do you think an audio transformer is the way to go or a 10uf cap on the negative input.
Ideally I would like to get the booster working with the battery for the detector.
Thanks again,
Andrew...
 
Yep,
All fixed now. I put in an 3kohm to 3k ohm Transformer, and now no more noise.
Thanks for all your helps with this, and pointing me in the right direction to getting it sorted out.
Andrew....
 

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