King Cobra PCB

[mayky]

Some scope pictures: disc mode
1. U9 pin 1
2. U9 pin 7
3. Q11 base
4. Q10 base

And a picture, my PCB

[mayky]

What freqvency u15 (PowerSupply) pin2 ? 560 Hz ?

[mayky]

I found a mistake. The 2N2222 to not use the same pinout p2n2222a. I Use p2n2222a, and fault.
What is transistor using the original Cobra? Can I use any BC..... transistors. I have yet.

[kt315]

yes, certainly, those are ordinary transitors, nothing so specific. BC..... and 2N.... PN... are clear US type manufacturing tr-s
and you must know more about than me in Lithuania. Lietuva is so tiny state you are not able to find it at a map
while US is HUGE and cover ALL CONTINENT. Lietuva is some kinda a point from your pen at paper you touch.

look W. Lahr schematic with ORIGINAL tr-s.

[mayky]

I changed the transistor, but the noise is now, just louder

[kt315]

I changed the transistor, but the noise is now, just louder

do not use NOTCH filter connected. YOU ARE ABLE READ WHAT I WRITE?

[mayky]

Notch filter is off.

[kt315]

a noise goes throught out U9-B Q8 U15 Q10 Q11 speaker. what new you open for me? I had (HAD) answered
on this matter lots times before but you do not wish read this forum. and again again again ask me why there is noise.
do you guess to hunt INSIDE YOUR ROOM OR WHAT??? or AT FIELD?
so WHY you ask me about 50Hz electric influence inside your room? if you broke your walls and roof
you discovery HUGE AMOUNT METALIC ARMATURE inside the concrete. so why you ask me why
the influence does not give you the repose? leave this matter and go into wood.

[kt315]

I changed the transistor, but the noise is now, just louder

you can block the noise like i did. i gave this mod many times. but that is FOR ROOM.
for field you have to be back a schematic to original.

[mayky]

THANKS

[kt315]

And a picture, my PCB

can you upload bottom PCB side pic?

[mayky]

Of course

[kt315]

thank you. seems OK. would like to look an orientation of R79 R80, be cause guys did a mistake setting them 180 grad rotated.

[mayky]

That would be a short-circuit.

[kt315]

its simplest noiseless RC filter you can see in much projects. also, some SMD's give the beginners
some practic to solder and not fear SMD. in projects I have to orient on lowlevel enthusiasts, not on gurus, just cause
them majority.