Author Topic: 555 timer, no output  (Read 477 times)

0 Members and 1 Guest are viewing this topic.

Offline nus

  • Contributor
  • Posts: 32
  • Country: au
555 timer, no output
« on: May 12, 2019, 03:46:07 pm »
ok so i have a 555 timer with no output, however it seems to make sense.
 

Offline nus

  • Contributor
  • Posts: 32
  • Country: au
Re: 555 timer, no output
« Reply #1 on: May 12, 2019, 04:06:32 pm »
so on the threshold i have 3.75v. so in a discharge state.
On the trigger i have 5v,on the oscilloscope it shows me a switching that is someting like 7v to 2.5v before c32 it is switching between 0 and 5ish
reset is high 5v
so im a bit stuck here, is the issue the dc offset caused by c32, since it never drops below 1.66. do i even count the dc offset caused by c32
Also is there a way to calculate the resistance of the transistor according to the the signal its receiving. want to know this to understand why the voltage is high
since
r22 is 33k
q5 is 37k i measured this while it was off
so the divider = 2.64 which would be enough to turn off the discharge, which might be grounding my output. however i think that is not ever turning on  because of  the dc offset

this is a williams system 6 mpu
« Last Edit: May 12, 2019, 04:21:50 pm by nus »
 

Offline nus

  • Contributor
  • Posts: 32
  • Country: au
Re: 555 timer, no output
« Reply #2 on: May 12, 2019, 04:07:19 pm »
i need the output to be high
 

Offline nus

  • Contributor
  • Posts: 32
  • Country: au
Re: 555 timer, no output
« Reply #3 on: May 12, 2019, 04:50:50 pm »
a is before c32 and b is trigger on pin 8
« Last Edit: May 12, 2019, 04:53:39 pm by nus »
 

Offline nus

  • Contributor
  • Posts: 32
  • Country: au
Re: 555 timer, no output
« Reply #4 on: May 12, 2019, 04:57:27 pm »
ok i just shorted the cap and now it works
 

Offline nus

  • Contributor
  • Posts: 32
  • Country: au
Re: 555 timer, no output
« Reply #5 on: May 12, 2019, 05:10:12 pm »
what are the issues with this. the cap measures the right amount 46nf, it has 473 marking on it. i dont understand why stock cap at correct value would be doing this. any ideas on what i should do
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf