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How to use the same RELAY on 12V & 24V vehicles

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NiHaoMike:
Remove C1 and replace it with a series RC combination from the base of Q3 to the collector of Q1, and also add some resistance in series with the base of Q2. Now you have a very simple switching converter.

Or it might be possible to just adapt this simple converter circuit:
http://romanblack.com/smps/a03.htm

Now I wonder if a LED driver chip might be the best solution. The buck kind generally is already designed to have the load connected on the high side and it would have an enable pin to allow the microcontroller to turn it on and off.

Zero999:

--- Quote from: NiHaoMike on August 19, 2019, 01:10:09 pm ---Remove C1 and replace it with a series RC combination from the base of Q3 to the collector of Q1, and also add some resistance in series with the base of Q2. Now you have a very simple switching converter.
--- End quote ---
Well it is a very simple switching regulator. Yes, there are other ways of getting it to oscillate. I agree about adding a base resistor to Q2. Omiting the base resistor was an error. :palm:


--- Quote ---Or it might be possible to just adapt this simple converter circuit:
http://romanblack.com/smps/a03.htm
--- End quote ---
Yes that's a good enough idea, but it requires an additional inductor.


--- Quote ---Now I wonder if a LED driver chip might be the best solution. The buck kind generally is already designed to have the load connected on the high side and it would have an enable pin to allow the microcontroller to turn it on and off.

--- End quote ---
I agree. You can get some cheap buck LED driver ICs very cheaply.

floobydust:

--- Quote from: mariush on August 19, 2019, 12:17:27 pm ---... did anyone mention bi-stable relays?

--- End quote ---
I find latching relays not so good in something portable or a car, anywhere they get bumped- they can unlatch. Then firmware wrongly assumes the relay is latched when it isn't, which causes more problems.

Richard Crowley:

--- Quote from: floobydust on August 19, 2019, 09:14:47 pm ---I find latching relays not so good in something portable or a car, anywhere they get bumped- they can unlatch. Then firmware wrongly assumes the relay is latched when it isn't, which causes more problems.

--- End quote ---
Unless you have a spare set of contacts that can be monitored by the microcontroller.

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