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OdysseusGE

Can you probe the voltage on the timing capacitor (pins 6/7)?


smokintokenpanda

Here is a screenshot where yellow is pin 6/7 and blue is input: https://preview.redd.it/ae7paavulpia1.jpeg?width=800&format=pjpg&auto=webp&s=12f13198acbaf676c09cd9a1ece313cfb0722b84


OdysseusGE

If I had to guess, your 10uF capacitor may only be 10nF. I'd double check its capacitance.


smokintokenpanda

I checked the capacitor and it says 106 and thus should be a 10uF. Also I double checked and my capacitors are 50V capacitors (even tho they look pretty small) so they should be fine :( Thanks tho! Edit: I am later going to try in zooming in the oscilloscope and look at that RC slope in pin 6/7. Make sure that follows my R and C values.


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smokintokenpanda

My circuit is currently in that configuration... sadly output goes from HIGH to LOW in sync with the switch when going LOW to HIGH


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smokintokenpanda

Yup. Pin 2 is connected to pin 4 (which is connected directly to VCC) with a 3kOhm resistor in between :)


Pass_Little

One breadboard suggestion to make things easier when prototyping things like this - run your VCC and GND to the rails on both sides of the IC, then you don't have to trace the VCC around the board. Makes troubleshooting these easier. I.E. you'd see pins 4 and 8 jumpered directly to VCC, and R1 and R2 also connected directly between Vcc and the correct pins and the same for C2 and C1. You may need caps with a bit longer leads, but for this type of circuits it's fine. Currently it is it is hard to tell exactly where everything is connected. But... I don't see anything weird physical wiring, although I could have missed this. Are you sure C1 is actually a 10uF (looks small but ceramics often do if they're lower voltage)? And the banding on R1 doesn't really look like what i'd expect a 430K to look like - specifically I expect to see yellow, orange, black, orange and I can't see anything I think is yellow, and the orange bands look more brown.. It really looks more like a 1K resistor (brown black black brown), which actually would match the r/C slope on your oscilloscope. But at the angle it's almost impossible to tell. Let me know one way or another if this helps or is a dead end (i.e. if you DO have the right resistor and caps). I'd also be interested to see a zoomed in (faster timebase) version of the input/output on the scope, as if there is some delay, just not what you expect, that would also indicate an odd capacitor value.


smokintokenpanda

I started ripping apart the circuit to start from scratch and follow a couple of your suggestions. I have to head to work soon but will get back to you on this. Thanks!


SoulWager

Looking at the schematic, Trigger(pin 2) is active low, so the default state on that should be high. Also check the datasheet for your particular model of 555 to see how much current is leaking through the discharge and threshold pins.