#### Thunderchild

##### New Member

Right the chalenge is on !

I did have a previous thread about this but now I know more of what I'm about we shall start from scratch !

I'm out to design a voltage regulator for vintage cars running on dynamo's my friend has a 1956 Jaguar (yes gets admiration wherever it goes) and other prewar cars he wants regs for. The electronic regs must fit into the original cases with no external modifications.

now as I understand it my working conditions are: keep output at about 14.5 volts (well his runs 13.6 but I say thats a bit low) and the maximum load is 30-35 amps so I want to build for 50 A to allow plenty of margin (apparantly 35 A is rare most are under 30).

Now I have to replicate each function of the old regulator being: voltage control, overcurrent protection and stopping the battery from discharging back into the generator when its output is low. At the same time as I'm building into original cases most of which are for 2 relay regulators so I have to account for how much heat I am generating and I'm not allowed to go putting holes in the original case

now I can easily stop the battery discharging into tha battery by using a blocking diode, I'm thinking again of a 60 ish amp capacity.

I can then control the voltage output by PWM the feild coil, I am thinking of a pic for this, that will produce a PWM output and will sample the output voltage and ajust the duty cycle accordingly.

For over current protection I was thinking of having a tiny series resistor and sampling the voltage over it and at a set threshold over ride the voltage control pulse value and reduse it to reduce the voltage and so reduce current, which might get to the point where it will cut off in the event of a short circuit.

Am I heading in the right direction ? does anyone know anything more and can point out a possible pitfall ?

I did have a previous thread about this but now I know more of what I'm about we shall start from scratch !

I'm out to design a voltage regulator for vintage cars running on dynamo's my friend has a 1956 Jaguar (yes gets admiration wherever it goes) and other prewar cars he wants regs for. The electronic regs must fit into the original cases with no external modifications.

now as I understand it my working conditions are: keep output at about 14.5 volts (well his runs 13.6 but I say thats a bit low) and the maximum load is 30-35 amps so I want to build for 50 A to allow plenty of margin (apparantly 35 A is rare most are under 30).

Now I have to replicate each function of the old regulator being: voltage control, overcurrent protection and stopping the battery from discharging back into the generator when its output is low. At the same time as I'm building into original cases most of which are for 2 relay regulators so I have to account for how much heat I am generating and I'm not allowed to go putting holes in the original case

now I can easily stop the battery discharging into tha battery by using a blocking diode, I'm thinking again of a 60 ish amp capacity.

I can then control the voltage output by PWM the feild coil, I am thinking of a pic for this, that will produce a PWM output and will sample the output voltage and ajust the duty cycle accordingly.

For over current protection I was thinking of having a tiny series resistor and sampling the voltage over it and at a set threshold over ride the voltage control pulse value and reduse it to reduce the voltage and so reduce current, which might get to the point where it will cut off in the event of a short circuit.

Am I heading in the right direction ? does anyone know anything more and can point out a possible pitfall ?

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