Originally posted by Altra
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Whites tdi pro shematic+pcb
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Like I mentioned above the schematic has some mistakes still. A major error I discovered a few days ago is D18 in the voltage doubler. The way it is connect in the schematic and on your pcb the whole circuit will not function. It will not generate the +5 volts. Google diode voltage doubler and compare to the schematicOriginally posted by sayan1345 View PostTDI PCB with Proteus
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Correct Detectorist. Also R6 the series resistor going to the coil is only 0.25 watt on the pcb. This will burn out right away. I think the minimum should be 2w or higher.Originally posted by Detectorist#1 View PostAttached is the picture of the PCB with correction of the connection of D18Last edited by Altra; 12-29-2025, 12:13 PM.
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Correct Altra. Average power on this resistor is appr. 2.5W. Also, serially to D8 is correct to put current limiting resistor 10K. Also C35 no need to be Not Polarized type. The marked polarity on the board is correct. The resistance of the speaker have to be not less than 32oHms for not overheating of LM386.
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The fake lm 386 heats up, the original one does not heat up at all in my TDI - I took it from some device, an old radio with original Toshiba components, they all heat up from China!Originally posted by Detectorist#1 View PostCorrect Altra. Average power on this resistor is appr. 2.5W. Also, serially to D8 is correct to put current limiting resistor 10K. Also C35 no need to be Not Polarized type. The marked polarity on the board is correct. The resistance of the speaker have to be not less than 32oHms for not overheating of LM386.
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It's probably not in Tdi sl, it has a zener diode that limits the voltage, I don't remember what the value is, but all the lm 386 from China heated up, some less, some more. If it does not heat up, I believe that the component is real, not fake!And as I remember, those Chinese ones had hum or noise, good lm 386, when the threshold is without tone, there is almost no noise at all.Originally posted by algan View PostI have connected the TDI power supply circuit of the LM386 integral to +5 and -5 volts and it works without any problems, it doesn't heat up and I don't know if it's fake.
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