atari punk color organ

[MrDEB]

curious if this has ever been done or even possible.
Am playing around building an Atari Punk Console but thinking of adding LEDs that are controlled by 3 band pass filters (low, mid high)
this is for another project for grandson to drive his parents nut with the sound and amuse him with the LEDs.

 

[MrDEB]

REVISING THE COLOR ORGAN. Using A SIMPLIFIED CIRCUIT THAT DOES NOT USE THE OP AMPS.
Original design used 2n3904 transistors, but using a MOSFET instead will conserve battery power a little
attached both designs

 

[Nigel Goodwin]

I don't see why you imagine the FET version would conserve any battery power?, at a quick glance it doesn't look like it would even work, with the FET's looking to be permanently biased ON?.

Both are utterly crap circuits anyway, and performance would be poor.

 

[MrDEB]

here is a video of the circuit with 2n3904 transistors.
My understanding and simulation using easyeda the PNP transistor loses about 1.5 volts aprox. The MOSFET way less.

 

[tumbleweed]

Original design used 2n3904 transistors, but using a MOSFET instead

Be careful. The original design uses a 2N3904 + 2N3906 transistors (the schematic shows the wrong symbol for the first transistor).

You can't just replace the 2N390x with a fet. Build the circuit as originally shown if that's what you want.

 

[Nigel Goodwin]

here is a video of the circuit with 2n3904 transistors.
My understanding and simulation using easyeda the PNP transistor loses about 1.5 volts aprox. The MOSFET way less.

Your understanding appears to be misplaced - 'if' the transistors are turned fully ON, then they will only lose a couple of hundred millivolts, but this poor circuit is unlikely to achieve that. I don't see how the FET circuit will improve on that?, it depends on how well they are driven - but the circuit you posted appears to have them permanently biased ON anyway?.

In any case it doesn't matter if you lose a little voltage across the transistors or FET's as LED's are current driven - you've already got series resistors to lose voltage and lower the current, the drop in the transistors/FET's is only going to add a little to that.

As others have said, you can't just repace transistors with FET's, and there seems no advantage anyway.

 

[MrDEB]

after making the changes as suggested I think I can make my grandson a kool toy

 

[Nigel Goodwin]

Well we're back on random circuit changes that will entirely stop it working

As you were told the FIRST transistor was drawn with the wrong polarlty, why did you leave that one wrong and change the other three?.

 

[MrDEB]

will check thanks
found my mistake, I had the 2n3906's upside down