Hey there. Just reading about mosfet rectifier bridges (article)

They show this diagram

I guess I just want to know... in the context of a retrofit, can this just be added to any old circuit at the battery in? I guess I'm visualizing that the battery + would go to either "IN~" and common GND would go to the other "IN~" as well as "- OUT" while VCC is "+ OUT"? Or is this circuit not really applicable to a common ground scenario?

Sorry if its a stupid Q.

- Steven

 

why not, the only caveat is that gate voltage limit must not be exceeded so this is usable only for low voltages.

 

Hey there. Just reading about mosfet rectifier bridges (article)

They show this diagram

I guess I just want to know... in the context of a retrofit, can this just be added to any old circuit at the battery in? I guess I'm visualizing that the battery + would go to either "IN~" and common GND would go to the other "IN~" as well as "- OUT" while VCC is "+ OUT"? Or is this circuit not really applicable to a common ground scenario?

The "IN~" connections are the AC source input. Why are you mentioning a battery?

A bridge rectifier requires that the input common be isolated from the output common.

Edit: Are you referring to a battery because you want to use the bridge so you can reverse the battery polarity and still get the proper output polarity?

 

Edit: Are you referring to a battery because you want to use the bridge so you can reverse the battery polarity and still get the proper output polarity?

Yes. it was my understanding the circuit could be used for that as well. I obviously should have mentioned that at the beginning... sorry. The source is roughly 7v to 12v DC. I'm just doing some retro work... and "add on" board that will plug into the existing circuitry at a wire harness. The purpose of which is unrelated to the power supply, but there have been complaints by the device's owners that several people have smoked them because the power input is ambiguously marked. Basically, the device was originally designed for a 8xAA NiMH setup but many people switch to a 2 or 3 cell LiPO and, unfortunately, the standard LiPO balance plug is the same physical plug that the device used for the 8xAA... but with different wiring. When end-users DONT READ (which is a lot of them), they assume the balance plug goes there (rather than soldering a connection for the discharge plug) and *POOF*. So I thought, while I was making this add-on board, that I could also dummy-proof the power input so that if they plugged in either the 8xAA or the LiPO, they'd be OK.

But, looking closer at the schematics for the original device, I don't think it will work anyway. The harness I'm "hijacking" has the battery in on it, which gave me the idea, but I'm a little downstream of the plug. In between, it branches off and goes to other circuitry anyway. So I wouldn't be protecting the whole device, and while that has some benefit... the dummys will still be dummys and they'll still destroy part of it. If I claim to offer protection, those same people that don't read very well will likely assume its fully protected, and now I'll be to blame for their mistake! I'm probably best leaving them to their own devices in this regard.

 

May sound dumb, but why not add a single schottky diode to the correct (+) line at the battery clip? A schottky,for a low voltage drop. The diode would need to be chosen that has a higher reverse voltage than the battery voltage though. And a high enough amperage rating. This would then protect the whole circuit.

 

Thanks, and that may have to do... but then it penalizes (in terms of battery drain) those that connect it correctly.