# Simulated 555 timer not working

I am a beginner in electronics.

I've been trying to make an astable 555 Timer in TinkerCAD as an oscillator for my own project of making a clock, without using internal timers in Arduino ( I know it's pointless, but it's a challenge I set for myself to learn more ). No matter what I've tried, the circuit gets stuck on high or if arranged in another manner, low and the capacitor doesn't seem to be doing anything, based on the serial log outputs.

I've compared it to existing schematics and it all seems correct to me. Help would be very much appreciated.

EDIT: I've trimmed the circuit down to the bare minimum to make it easier to understand..

• I'm having the same exact issue. And I'm almost certain my wiring is correct. I believe this is a bug in the TinkerCad code. Did you ever find a solution? I say this because I've also googled "tinkercad 555 timer" and found other people's simulations. When I run those, nothing happens as well.
– user236894
Nov 25, 2019 at 2:40

You need a ground connection to pin 1 of the 555 timer.

• Oh yeah, I was reorganising my circuit to a new form and missed the ground pin... even then, the circuit is stuck at high, but at least, I am getting closer.. Jul 4, 2019 at 13:22
• The output will be mainly high with short negative going pulses.
– user173271
Jul 4, 2019 at 13:24
• So, that means the circuit indeed is correct, I just have to adjust the capacitance and resistances to get a good pulse. Correct? Jul 4, 2019 at 13:26
• The circuit looks fine to me. Increasing the value of the capacitor will increase the duration of both the mark and the space but will not change the ratio between them. Increase the value of the 1k resistor to lengthen the duration of the negative going pulse.
– user173271
Jul 4, 2019 at 13:30
• That looks like a small value capacitor which in conjunction with the small 1k resistor results in a very short negative going pulse. Tmark = 0.7(R1 + R2 )C. Tspace = 0.7*R2*C where your R2 = 1k.
– user173271
Jul 4, 2019 at 13:50