Author Topic: Safety cutoff circuit troubles  (Read 754 times)

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Offline PentoadTopic starter

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Safety cutoff circuit troubles
« on: December 26, 2019, 02:52:43 pm »
I am designing a system where a relay is turned off for some time when a voltage is present at the input pin. When the voltage is present, C1 is discharged and the relay switches off as it's meant to. The only issue I'm struggling with is when the circuit is powered up for the first time, I have to wait about a minute for the capacitor to charge and the relay to switch on. How would I change the circuit so that C1 is charged once when the circuit is powered meaning that I don't have to wait for it to switch on?



« Last Edit: December 26, 2019, 10:14:35 pm by Pentoad »
 

Offline MiDi

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Re: Safety cutoff circuit troubles
« Reply #1 on: December 26, 2019, 09:13:35 pm »
As a starting point:



There are a couple of issues with this, can you figure out which?
Any ideas to fix the issues?
« Last Edit: December 26, 2019, 09:16:31 pm by MiDi »
 

Offline mk_

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Re: Safety cutoff circuit troubles
« Reply #2 on: December 26, 2019, 10:06:39 pm »
How would I change the circuit so that....


at least polarity of Q2 is not how it should be...
 

Offline PentoadTopic starter

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Re: Safety cutoff circuit troubles
« Reply #3 on: December 26, 2019, 10:17:01 pm »
Easyeda seems to always give me upside down transistors and I forgot to flip it.
As a starting point:

(Attachment Link)

There are a couple of issues with this, can you figure out which?
Any ideas to fix the issues?

I can't help you without a description of your problem.
« Last Edit: December 26, 2019, 10:18:35 pm by Pentoad »
 


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