simple cycle timer

[dosensuppe]

Hello. Thought this thing would be simple enough, and ofc I tested everything on breadboard beforehand. It's just a counter which pulls the tranny low every period, hence activating the NE555 monoflop. But after etching my PCB I can't get the friggin NE555 monoflop to work. Everything else works fine.
Please just tell me I made some stupid mistake wiring something up.

[WattsThat]

High value 555 timing caps are not a good idea… C4 leakage? Monitor the voltage on C4, if it starts to ramp up and fails to reach… what is it, two thirds VCC?, the 555 will never change state and remain stalled since the comparator trip point is never reached. Maybe a tantalum rather than a cheesy electrolytic but even that’s no guarantee.

Q2 base drive could be too low as well at 500ua if the 555 never releases and starts to ramp up voltage on C4.

[Smile2016]

Check Q2's footprint , then the potentiometers .... cheers ! Check D1 orientation...

[synccond]

Move the 4060 to the output of the 555, allowing better operating frequency for the 555.  You should be able to use a bare bones simple oscillator at lower freq to feed the 555, rather than crystals and divide-bys.  What kind of accuracy is really needed, after all.

[Zero999]

Are you sure about putting 24V on a USB connector? That could lead to smoke, if something which expects 5V is plugged in.

Switching the ground can also cause problems. If the power supply to your circuit is earth ground and you use it to switch something who's 0V is also connected to earth ground, then it won't switch it off, because the current will find a path throuh earth ground, bypassing the switching transistor.

Finally, have you considered using a small microcontroller? As well as being cheaper and simpler, the internal RC oscillator will be much more accurate and stable, than discrete components.

[PCB.Wiz]

Hello. Thought this thing would be simple enough, and ofc I tested everything on breadboard beforehand..
. But after etching my PCB I can't get the friggin NE555 monoflop to work.

If it worked fine on the breadboard, look for shorts or opens on your etched pcb.
Did you clean it thoroughly?
Also check with a lower pull-up and timing cap, in case the pcb has poor cleaning leakage problems.

[dosensuppe]

It was a very stupid issue. it turns out the 555 GND connection was an island which I was unable to notice.
Since wanting to avoid a double sided board, I set simple wire jumpers which I made using a footprint with 2 equal pin numbers, but the DRC did not register that, so threw out all kinds of warnings which I just ignored.

Any ideas on a better way to set wire jumpers in KiCAD that are registered as connections by the DRC?

[Doctorandus_P]

Any ideas on a better way to set wire jumpers in KiCAD that are registered as connections by the DRC?

A simple way is to draw it as a double sided PCB in KiCad, and then only draw "straight wires" on the front of the PCB. Then also adjust the via size and drill diamater, so you can easily solder some wires into it.

For KiCad, it's just a double sided PCB, so DRC is happy.
For yourself: There is no need to put it in the schematic, so that stays clean.
And the tracks on the front copper layer are also a visual aid for where you need to put the wire bridges.

[Sacodepatatas]

Any ideas on a better way to set wire jumpers in KiCAD that are registered as connections by the DRC?

A simple way is to draw it as a double sided PCB in KiCad, and then only draw "straight wires" on the front of the PCB. Then also adjust the via size and drill diamater, so you can easily solder some wires into it.

For KiCad, it's just a double sided PCB, so DRC is happy.
For yourself: There is no need to put it in the schematic, so that stays clean.
And the tracks on the front copper layer are also a visual aid for where you need to put the wire bridges.

That's what I do when protoboarding.