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Digital oscilloscope project/kit

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RobWilson:
 :lol: Hog roast would fit in the van Dave  :lol:

I will look into it , are you going mate ?


Rob

Bluechip:
If you know the current the welder takes and for how long it takes it a first approximation would be:

Say ... 50A for 0.2 seconds ...

I x T = 1/2 ( C x V2 )

So: Assume 50A for 0.2 seconds and an applied voltage of 35V

C = ( 2 ( I x T )) / V2

Which I make about 16 and a bit mF  or 16,500 uF

This does assume the cap. voltage stays at 35V all the time which it won't ...  :(

No real idea what current a spot welder takes or for how long?

Don't they have some sort of timer to gate the current ?? Another easy job for a PIC ...  :beer:

Dave

Bluechip:

--- Quote from: RobWilson on May 03, 2016, 04:19:53 PM --- :lol: Hog roast would fit in the van Dave  :lol:

I will look into it , are you going mate ?


Rob

--- End quote ---

Yup, got my ticket   ... Codgers Discount rate ...  :thumbup:

Saturday probably ... about 90% certain.

D.

Bluechip:
Have you got a diagram of what you want to build ... ?

Not having any real idea of how these things work, it seems to me to use a thyristor as the switching element as these turn off anyway when the current drops below the holding value and it wont switch on again until another gate pulse arrives ...  :scratch:

D.

PK:

--- Quote from: RobWilson on May 03, 2016, 03:01:26 PM ---Ok lads

A question for the electronics chaps ,   I would like to build a circuit that would charge up a bank of capacitors to anywhere between say  10v  to  35v and when charged  to the set voltage disconnect the power supply from the capacitor bank .   

Any pointers ?   :scratch:


Rob

--- End quote ---

The details depend on things like how: how big the caps are, how fast you want to charge them, and what your input voltage to this circuit will be.

But essentially you would use a current limited power supply set to the target voltage and a diode. Very simple for small (ie <=10A) currents.
PK

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