From: amdx@knology.net
On 2/1/2021 5:26 AM, John Doe wrote:
> Rich wrote:
>
>> John Doe wrote:
>>> Rich wrote:
>>>> John Doe wrote:
>>>>> I can put a resistor after a voltage that's too high for the circuit?
>>>>>
>>>>> Of course the resistor must handle the current.
>>>>>
>>>>> A decoupling capacitor after the resistor.
>>>>>
>>>>> Any problems with that?
>>>> If your load has a variable current draw, then you will also have a
>>>> variable voltage on the load side of the resistor.
>>> If it's a big capacitor, the voltage variation is minimal?
>> No, the size of the capacitor simply determines the rate at which the
>> voltage changes.
> Then your answer should be "Yes", given the same amount of time.
>
> Why are you fighting this?
>
> Do you think it makes you look smart?
 Now you have made yourself look ignorant, which you are, otherwise you
would not have ask the question.
 Say your device needs 9V and you have a 12V source. At some point in
time you measure the current your device draws and it is
20ma, so you decide you need a series 150 ohm resistor. You have it all
figured out. Then at some point it fails to work.
At some point the motor in this device (the one you didn't explain )
turns on and the voltage drops to 4 volts causing the circuit to fail to
operate.
 Do you want to calculate the capacitance needed to keep you supply
voltage within 5% of your required 9v?
Or do you want to just admit it is a big ass cap and a regulator may be
better.
On the other hand you could give us details of the circuit, so it would
not be a guessing game.
                               Â
                 Mikek
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