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A relay polarity switching circuit needed..

teletups

Mar 5, 2023
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hi, is anyone willing to point me to a circuit for this relay polarity switching:

I need to use it directly with a 9v battery (no Arduino needed)


thanks :)
 

dragon

Oct 31, 2022
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I dont know where it would be on the internet
but I can draw this circuit myself, if u want me to! :)
But I haven't ever used a real relay before, so I almost could do it, not quite.

But haven't already made the circuit yourself - why do you need it?
 

teletups

Mar 5, 2023
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I dont know where it would be on the internet
but I can draw this circuit myself, if u want me to! :)
But I havent ever used a real relay before, so I almost could do it, not quite.

But havent already made the circuit yourself - why do you need it?
YES! i would be so thankful!
 

dragon

Oct 31, 2022
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Ah I UNDERSTAND NOW! U WANT AN OSCILLATOR!!!!!

I thought you just meant u only wanted to it to run off the arduino, so I didn't read properly.... :p
Well, I have another post here with the circuit in it, and this post appeared as if by magic straight afterwards.

Heres an amped discharge style oscillator->

If you put a capacitor on both relays, and make the capacitor discharge through its relay each (to turn the relay on), and the relay charges the opposite capacitor, that kinda gives you an oscillation, but it doesnt quite work unless u bias it. (It will stall and finish with both relays going together.) I havent quite finished it yet sorry... I cant fully help you.

Sorry...
 

dragon

Oct 31, 2022
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hi dragon! can you send a link to this: amped discharge style oscillator
I would love to help with that, But I actually came up with it myself, there is no link to it.

But there is other oscillators to look at, here ill send you one->
(just replace the transistors with relays should be fine.)
 
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Bluejets

Oct 5, 2014
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just replace the transistors with relays should be fine.)
Don't think so......schematic you show relies on one transistor removing bias from the other.
Most relays don't care about polarity or bias levels only pull in voltage/current.
Futhermore, bad idea as relays will not react as you expect over a certain frequency.
 

Harald Kapp

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Nov 17, 2011
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But I haven't ever used a real relay before, so I almost could do it, not quite.
Then stop offering a servbice you can't provide.
I didn't read properly
Not your first time.
(just replace the transistors with relays should be fine.)
Definitely not. That is BS... The transistors do the switching.

@teletups : Beware of @dragon 's "advice".


anyone willing to point me to a circuit for this relay polarity switching:
That video is imho next to useless. No circuit diagram given. Blinking circuits can be found by the dozen on the internet. Please describe what you want to do, then I'm sure we can find a simple solution.
 

teletups

Mar 5, 2023
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i have a 9-12v battery and an electromagnet.
the circuit must be able to switch battery polarities at 1-20 times per second (switching time is adjustable with a potentiometer) I need the simplest circuit possible using common electronic parts
 

Harald Kapp

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the circuit must be able to switch battery polarities at 1-20 times per second
While possible with a relay, this is a bad option. A typical general purpose relay has an endurance on the order of 2 × 106 switching cycles (see e.g. this datasheet).
[math] 2 × 10^6 cycles / /frac{20 cycles}{second} = 10^5 seconds \equiv 27.8 hours[/math]You'd be replacing relays on an almost daily basis.

For this application a much better option is a H-bridge (tutorial) controlled e.g. by an astable multvibrator built from a 555 timer (tutorial).

The H-bridge can be bought as a module, e.g. this one.
The timer can be bought as a module, e.g. this one.
Since the H-bridge module expects 2 control signals for the direction (aka polarity), you will have to add an inverter between the 555 module and the H-bridge module to create the 2nd signal (example).

Alternatively you could use an Areduino to create bot signals and the timing.
 

Delta Prime

Jul 29, 2020
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You say you have an electromagnet could you elaborate. did you buy it?did you make it yourself? did you find it on the ground?We need to know the specifications of your electromagnet, your coil's inductance and winding resistance the ampacity of the magnet wire in the electromagnet? you have 9 volt DC battery and wish to switch(reverse) the polarity of that battery at 20 times per second. Now you have left DC and have entered AC with AC comes impedance & impedance is frequency dependent .Can you go faster than 20 times a second a larger frequency? You'll have to be able to dissipate a large amount power in watts,P= I squared R in the form of heat with your electromagnet .Could you describe your electromagnet in more detail?
 

teletups

Mar 5, 2023
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While possible with a relay, this is a bad option. A typical general purpose relay has an endurance on the order of 2 × 106 switching cycles (see e.g. this datasheet).
[math] 2 × 10^6 cycles / /frac{20 cycles}{second} = 10^5 seconds \equiv 27.8 hours[/math]You'd be replacing relays on an almost daily basis.

For this application a much better option is a H-bridge (tutorial) controlled e.g. by an astable multvibrator built from a 555 timer (tutorial).

The H-bridge can be bought as a module, e.g. this one.
The timer can be bought as a module, e.g. this one.
Since the H-bridge module expects 2 control signals for the direction (aka polarity), you will have to add an inverter between the 555 module and the H-bridge module to create the 2nd signal (example).

Alternatively you could use an Areduino to create bot signals and the timing.
Thank you Harald for your help!

can I use this 555 timer? https://www.circuitbasics.com/555-timer-basics-astable-mode/

how to connect the h-bridge(https://www.modularcircuits.com/blog/articles/h-bridge-secrets/h-bridges-the-basics/) with the inverter to an above timer?
 
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