PI Audio

[dom44]

this is how i made mine but i added a LM386 amp stage this VCO is a good circuit,

[Mdtoday]

this is how i made mine but i added a LM386 amp stage this VCO is a good circuit,

[ATTACH]45447[/ATTACH]

Great work Dom44, thanks for sharing

cheers

Mdtoday

[dom44]

I made it as compact as i can using standard components you should check it i tested on the bench but haven't installed it in a detector yet.

[Mdtoday]

I made it as compact as i can using standard components you should check it i tested on the bench but haven't installed it in a detector yet.

Ok, will check it, could you post a schematic if you have one please .

thanks

Mdtoday

[dom44]

I will draw it up give me some time, it is the same circuit you posted just added the LM386.

[Mdtoday]

Dom44,

I noticed you don't have the 2.2uF input cap on the board, was that intentional?

I'll build up another couple of boards and try a few different Opamps too.

cheers

Mdtoday

[dom44]

I was going to put it on the detector end ran out of room I will see if i can fit it in.

[dom44]

just squeezed it in bit better vco- added a 100uf decoupler cap to amp on this one should be it now

[Mdtoday]

just squeezed it in

[ATTACH]45449[/ATTACH]

Good job and thanks

cheers

Mdtoday

[Mdtoday]

I will draw it up give me some time, it is the same circuit you posted just added the LM386.

Thanks Dom44, no worries, at least this way it will match your PCB layout.

cheers

Mdtoday

[Mdtoday]

just squeezed it in bit better vco- added a 100uf decoupler cap to amp on this one should be it now


[ATTACH]45451[/ATTACH]

Hi Dom44,

Just a couple of things I spotted, see markup

1) the 10k input resistor to 4046 pin 9 should be direct to output of first opamp
2) You have a 20k resistor marked instead of 220k.
3) I would suggest using a 10 turn preset for the input offset for finer zero adjustment

Cheers

Mdtoday

[dom44]

thanks Mdtoday i think i have sorted it you are right my circuit is the hand drawn one the 220k looked like 20k should be ok now put in a 10 turn and moved the 10k resistor the 10k explains why my the LED's where not working correctly.

Dom44

[Mdtoday]

No worries Dom44, I did a quick spice of your circuit with lm324 and it appears to be fine, didn't check drift but should be ok

One last suggestion if I may, perhaps 3.2mm mounting holes in or near corners if you can increase pcb size, that way even with panel mount pots, you can relieve stress on them using the mounting holes and spacers to main board or enclosure.
Even a couple on oposite side to pots would do it.. 8 mm corner clearance will avoid shorting -5 v to case etc. Hope this helps and good work btw

cheers

mdtoday

[dom44]

how about this one?

[Mdtoday]

how about this one?

[ATTACH]45456[/ATTACH]

Yes, that looks more robust, good job