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Need suggestions for alternating power in circuit? Answered

Hi all,
I am working on a little circuit that uses a potentiometer to send a pulse to a piezo, I would like to install another pot with different settings and automatically alternate the pulse between the 2 pots. Power would need to be redirected to each potentiometer alternating for approx 15-20 sec.
So when I power on, there will have a 20sec pulse using potentiometer #1 then 20 sec using potentiometer #2 and so on...
The circuit works on a 1.5v to 4.5v dc power source. There could also be a delay between the 2 different pulse.
What would you suggest using as the switching hardware  ... ic ... chip? The circuit is working right now but uses only 1 potentiometer with 1 set pulse, I just want to add another pot.
Thanks for all inputs, looking forward to hear from you.


Lion_Heart

Tags:circuit

12 Replies

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steveastroukBest Answer (author)2012-02-17

Connect the common of the relay to the base of Q1, connect the NC pin to the track of the 1st pot, connect the NO pin to the track of the second pot. Connect the wiper of both pots to the end of R2.

Steve

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Lion_Heart (author)steveastrouk2012-02-18

Many Steve and Verence, you guys are great.
Here is a schematic I have made with the relay and the 555 incorporated to the circuit.
The 555 does not have all the components attached yet but I just want to know if power ground and out are ok with 555, relay and circuit.
Thanks again

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steveastrouk (author)Lion_Heart2012-02-19

Try this - note values for the resistors, this will give you pretty close to 50/50 cycle, at 40 seconds/cycle

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Lion_Heart (author)steveastrouk2012-02-19

SUPER :) , this is excellent, I wasn`t expecting the whole thing, I will try it tomorrow and let you know.
Again Steve, many thanks for your time, it is very much appreciated.
Paul

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Lion_Heart (author)steveastrouk2012-02-17

Steve,
Concerning the relay, if my circuit is powered by 1.5v dc I will need a 1.5v relay or can a 12v relay be triggered by lower voltage or is "12v relay" means the max voltage it can take? And the 555 timer, would you put it .... between the base of Q1 and the common pin of relay?
Thanks for the reply, it is very much appreciated, it is of great help ;).

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steveastrouk (author)Lion_Heart2012-02-18

Relay voltage usually refers to the voltage required to make the coil pull in the contacts, so a "12V relay" usually means a relay which will pull in when 12V is applied to it.

The 555 timer will be switching your relay coil , it has no relationship to your existing circuit, apart from switching the two pots around for you.

The lowest voltage relay you are likely to get is a 5V coil, so you need 5V to drive the thing.

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verence (author)steveastrouk2012-02-18

+1

'12V Relay' means the relay  was designed to work with a 12V supply. If you supply a voltage close to 12V you'll be fine. Relays will work with lower voltages and higher voltages. How big that range is depends on the relay. for a 12V relay, 11V/13V should work, 9V might work or not, 15V might work or fry the coil. The farther you go away from the nominal voltage, the more likely is it not to work.

A 1.5V drive for a 12V relay? No way. Even a 5V relay will most probably not work with this voltage.

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lemonie (author)2012-02-17

Continuous and pulse are contradictory.
How do you imagine pluses being created with pot's?

L

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Lion_Heart (author)lemonie2012-02-17

lemonie,
Thanks for pointing that out, I completely understand the difference and I`ve edited my question.
Now, beside rephrasing and/or grammar mistakes what would you suggest as an option to help me here? How would you solve it?
I will try to insert a picture of the circuit.

Thanks again

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lemonie (author)Lion_Heart2012-02-17

The diagram helps a lot. I's go with steve because I've got a bad head today and he does know these things.

L

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steveastrouk (author)2012-02-17

Ah, I see. What you need is a relay, to switch the two pots into/out of circuit, drive them from a 555 timer.

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