Very low power consuming timer circuit

[Dknot--]

Hello,

I would want to construct (monostable) timer circuit, which would pass current after certain time period. This circuit would be triggered with voltage pulse.
The problem is, that I would want circuit to have a very low current consumption, maybe even just some microamperes.
Is it somehow possible to do this kind of timer circuits? I have already one low power 555-component, but it takes still a >100uA of current.
It would be very helpful, if some of you guys have clue for this problem.

Thanks for your answers!

-Dknot--

 

[MikeMl]

How much current do you want to pass after the time delay?

How much voltage do you have available to run the circuit?

How much voltage drop can you tolerate across the switching element after it turns on?

 

[Ubergeek63]

Hello,

I would want to construct (monostable) timer circuit, which would pass current after certain time period. This circuit would be triggered with voltage pulse.
The problem is, that I would want circuit to have a very low current consumption, maybe even just some microamperes.
Is it somehow possible to do this kind of timer circuits? I have already one low power 555-component, but it takes still a >100uA of current.
It would be very helpful, if some of you guys have clue for this problem.

Thanks for your answers!

-Dknot--

seems like i answer this one a lot too.... a schmidt trigger is not quite as accurate as a 555 but neither is more accurate than the 10% cap anyhow.

an RC on the input and a power switch on the output only draws a few uA

 

[crutschow]

You could use a CD4047B CMOS Multivibrator. It uses only a few microamps max. when quiescent.

 

[Dknot--]

MikeMl:

-My circuit would pass the current of, let's say 20mA when switched ON.
-The voltage available to run the circuit would be something like 2-3 volts.
- Voltage drop over switching element should be quite a small, because I want power consumption of timer circuit to be small.
Do you remember the circuit you described in your post to topic "Very Low Power Variable Resistance Switch"? Well, I build that circuit. It is working fine, (eventhough it seems that sometimes P-Mosfet in that circuit does not switch OFF-state after passing current in ON-state. It would be interesting to know why that happens. Do you have a clue?) so thanks again for your design!
Now I would want timing option for that circuit. Timing option would ensure current passing for some minimum time, let's say one minute. If temperature would switch the variable resistanse circuit OFF-state, timing module would still pass the current. If temperature would not switch the variable resistanse circuit OFF-state, timer module would have no effect for action of the circuit.

It would be either external module, or tuned variable resistor switch circuit. I 've had several attempts to build this, but I haven't been satisfied with the result.
Even though I believe there is simple solution (for everything^^).

 

[Dknot--]

Ubergeek63:

Hello,

What you mean with 10% cap ?

You told that an RC on the input and a power switch on the output only draws a few uA. Would there be any example circuit diagrams etc. about the circuit you mean? I'm still pretty much newbie to electronics, this is my third project ^^.

BR,

-Dknot--

 

[Dknot--]

crutschow:

CD4047B seems like an interesting component, and with a very reasonable price. It will be in my next electornics component order.

Thanks for replies to you all,

-Dknot--

 

[ronv]

Make sure you have 3 volts to run the CD4047. 2 volts may not work> see data sheet.