Permanent Magnet DC Regulator

[Nigel Goodwin]

would it be possible to have something that is on when the voltage is below, say 14v and... and it'll turn itself off when the voltage goes beyond 14v.

It'll act like a switch... so I can maintain a 14v charging... and when it's beyond 14v It'll just turn itself off... so I won't need to dissipate heat.

It's possible, but probably NOT a good idea, leaving the alternator disconnected may produce too high voltages? - in my experience such systems have always shunt regulated, presumably there's a good reason for doing so?.

 

[icedeocampo]

It's possible, but probably NOT a good idea, leaving the alternator disconnected may produce too high voltages? - in my experience such systems have always shunt regulated, presumably there's a good reason for doing so?.

hmm... I'm not removing the original regulator... I'll just tap it... parallel to the original regulator hehe...

I've got myself a decent heatsink and a fan... I'm now going to test it live in my bike hehe... hopefully i won't need the active cooling.

looking forward, what do i need to do to make a transistor normally conducting, and it will stop conducting at a certain voltage? would that be possible.

 

[Hero999]

I don't know how they work , if you'd be able to come up with some diagram and those MOSFET part numbers, I'm willing to try them out =).

Then Google for a tutorial about how they work. Learn about n-channel MOSFETs first, then apply the knowledge to p-channel MOSFETs.

 

[Nigel Goodwin]

Then Google for a tutorial about how they work. Learn about n-channel MOSFETs first, then apply the knowledge to p-channel MOSFETs.

What advantage would a MOSFET give over a bipolar in this application?.

 

[icedeocampo]

i've implemented it.. with the heatsink, it seems to be able to handle the heat... but I've fried 6 transistors in the process... when the voltage reaches around 25v-28v It kills the transistors...

RIP:

3pcs MJ15016
3pcs 2n3055a

Any ideas on how to fix this

 

[Nigel Goodwin]

How can the voltage reach 25V-28V, the shunt regulator should be holding it at around 13.8V? - and if the regulator isn't, the battery will.

 

[icedeocampo]

I did not connect it to the battery yet, I was just testing it if it would be able to control the voltage. I was afraid that if I connect it to the battery and the voltage shoots up, it might damage the fuel gauge and other devices connected to that line.

 

[Nigel Goodwin]

The transistor/zener should still hold the voltage down to 13.8 or so, if the voltage is going higher than that, then something is blown.

 

[Hero999]

What advantage would a MOSFET give over a bipolar in this application?.

None, sorry I wasn't thinking straight.

 

[icedeocampo]

The transistor/zener should still hold the voltage down to 13.8 or so, if the voltage is going higher than that, then something is blown.

Everything works perfectly up to around 25v... afterwhich the transistor dies, maybe the transistor isn't suppose to suck up that much power.

I now have a total of 7 transistors. As soon as I rev the bike... the transistor dies, is there something that causes the transistor to fry?

 

[Nigel Goodwin]

Everything works perfectly up to around 25v... afterwhich the transistor dies, maybe the transistor isn't suppose to suck up that much power.

I now have a total of 7 transistors. As soon as I rev the bike... the transistor dies, is there something that causes the transistor to fry?

Like I said, why are you getting 25V?, the zener and transistor should limit it to 13.8V or so - but it's certainly going to take a hammering without the battery connected, it's there to take the excess, not to take the full output of the alternator.

 

[icedeocampo]

i've been reviewing my implementation, and the only thing that seems to be wrong is the resistor. i think the resister is a pulldown resistor so, if it's not connected the circuit will still work right?

 

[icedeocampo]

i've again burned a transistor...

is it possible that the half wave rectification i've done is not good enough for the transistor to work properly?

or some freak ... voltage reversal happens on the transistor collector and emitter that fries the transistors..

 

[Nigel Goodwin]

As you never reply to any questions it seems pretty pointless carrying on?.

 

[icedeocampo]

I'm really sorry, I'm not ignoring your question but , I simply do not know how to answer your question. I really have no idea how the circuit works, you actually designed the circuit.

I've reviewed everything.. and I really have no idea why I get 25v... that is why I can not answer that question, all I can do is try to review my implementation.

I don't know why I get voltages far beyond the zener diode's rating.

 

[icedeocampo]

i guess theoretical implementations on paper has it's limitations.

 

[Nigel Goodwin]

Certainly does when trying to fault find without any tests or measurements been taken! - my psychic abilities are a little week this year

 

[icedeocampo]

what data do you need? I can do measurements or even come up with pictures of the setup.

i got myself 3 more 2n3055s I'm guessing that the transistor needs protection diodes...

 

[Nigel Goodwin]

what data do you need? I can do measurements or even come up with pictures of the setup.

You need voltage readings from all the component junctions, so we know what's wrong - as I said, you can't have 25V unless somethign is seriously wrong. It would also be handy to know what is failing, and in what way?.

i got myself 3 more 2n3055s I'm guessing that the transistor needs protection diodes...

I thought you were using a PNP transistor?.

 

[icedeocampo]

sorry for the late reply... elections and stuff here in the philippines...

I ran out of the PNP - MJxxxx transistors...

so I'll just do the experiment with the 2n3055s

i'll keep you posted...