Compressor timer

Thread Starter

soda

Joined Dec 7, 2008
177
Hi to all,

All i want the timer to do is to switch on a compressor and when it turn off,the buzzer has to sound for 3 seconds.

The one moment it does, and the next moment it don't. The buzzer is a bit unpredictable, so why is that?

I'll appreciate all the help i can get.
 

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R!f@@

Joined Apr 2, 2009
9,682
Hmmm.......couple of guesses.

Check relay contact.
Check buzzer.
check for loose connection or solder joints.
 

Thread Starter

soda

Joined Dec 7, 2008
177
Rifaa,

What about the relay contacts? It's a new relay and every things is working. It's just the buzzer that don't sound every time. It looks more like there's a problem with the mono stable to me,

If i turn on the circuit for the very first time, every thing is working, but when i want to use the compressor a second time, still wile the power is on, the buzzer doesn't sound.

Maybe i have to add a reset to it.
 

Thread Starter

soda

Joined Dec 7, 2008
177
Rifaa

I find a similar threat where Bill reply's. I'm gonna follow it and see if he come up with something i can use.It's the thread about the prob.

So thanks for your help mate
 

praondevou

Joined Jul 9, 2011
2,942
Rifaa,

What about the relay contacts? It's a new relay and every things is working. It's just the buzzer that don't sound every time. It looks more like there's a problem with the mono stable to me,

If i turn on the circuit for the very first time, every thing is working, but when i want to use the compressor a second time, still wile the power is on, the buzzer doesn't sound.

Maybe i have to add a reset to it.
I would leave IC2 always connected to the power supply and trigger it with the negative edge of the output of IC1.

You can couple the output of IC1 via a capacitor as in here:
 

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R!f@@

Joined Apr 2, 2009
9,682
One Q...

How long does it take to for u to have the compressor off so that the beeper sounds.

Is it more than 15 mins or more.

Can u take a voltage measurement while it is operating with a DVM
 

GetDeviceInfo

Joined Jun 7, 2009
1,666
This is one of those BAD NEWS circuits. Wiring both your power and control into a little black box is BAD business. Your problems haven't even started yet.
 

Thread Starter

soda

Joined Dec 7, 2008
177
I would leave IC2 always connected to the power supply and trigger it with the negative edge of the output of IC1.

You can couple the output of IC1 via a capacitor as in here:
I'm not sure if i'm with you here. What about the relay. I still wanted to power on and off the compressor. This is what's it's all about. When the compressor turns off, the buzzer has to sound for a couple of seconds to warn me the compressor stops
 

Thread Starter

soda

Joined Dec 7, 2008
177
Rifaa,

Sorry mate. I set up ic1 to run at 5, 10 or 15 min. This compressor is to make bubbles in a liquid and it all depends on what time i want the compressor to run on.

If it's a cold day then you need more time for the ferric chloride to do the job
 

Thread Starter

soda

Joined Dec 7, 2008
177
IC..

Tell me, have u killed any timers lately ?
Ha,ha! you mean kill with a hammer. Sometimes i really feel like doing it, but as far as i know, no i didn't kill a timer or any other thing.
Or did you mean kill time. I never kill time because time is always a good thing.
 

praondevou

Joined Jul 9, 2011
2,942
I'm not sure if i'm with you here. What about the relay. I still wanted to power on and off the compressor. This is what's it's all about. When the compressor turns off, the buzzer has to sound for a couple of seconds to warn me the compressor stops
The output of IC1 goes to the transistor that turns on the relay AND to the circuit I drew to trigger the second 555 on the negative edge of the output of IC1. (I didn't draw the existing transistor)

Connect the power supply of IC2 directly to the same power supply of IC1, don't pass it through the relay.
 

Thread Starter

soda

Joined Dec 7, 2008
177
The output of IC1 goes to the transistor that turns on the relay AND to the circuit I drew to trigger the second 555 on the negative edge of the output of IC1. (I didn't draw the existing transistor)

Connect the power supply of IC2 directly to the same power supply of IC1, don't pass it through the relay.
I didn't do exactly as you said but what i did, was to connect pin8 to the 12v rail as you said.

Please have a look at my circuit the way I've changed it now. It's working now, so thanks alot for your input. I really appreciate your help

Some error happen when i try to upload the pic,but i'll do it tomorrow before 12 AM
 

Thread Starter

soda

Joined Dec 7, 2008
177
I really meant it.

Timer, the 555 IC. ....Has any chip faulted. When the buzzer does not sound.
No, The 555 is still in a good condition. I've tried to upload my new edited schematic, but some error kicked in so, i'll do it later today. It's working now.

Many thanks mate
 

R!f@@

Joined Apr 2, 2009
9,682
Is the Cap discharging properly in that manner. ?

If it cannot discharge then timer won't work in the successive cycles. I think this is why u are getting one time buzzes. It is discharging over time.
 
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