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# Freddybaby

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1. ## high voltage probe (0-30kv)

Is your application for just DC or do you need compensation for HF (Like a scaled up scope probe) ? Also, the load resistance of your meter/s must be consistant as this will affect the ratio. Simple DC method 30 1M, 1000V rated resistors ( or whatever you can find for 30KV) To determine the low voltage resistor (R2) R1 (30M) / Ratio-1 (Lets say 1000/1 ratio) 30M/999 = 30,030.03 (This is the effective tap resistance) Then determine the parallel resistance across your load (meter) to get the proper ratio. (10M * 30,030.03 ) / (10M - 30030.03) = 30,120.48 ohms There are other factors to consider such as temperature and voltage coeffecient and possible corona discharge at above 15KV. This can be reduced with large conductor sizes and potting (difficult to do correctly). Good luck
2. ## Determining the frequency of a transient

Trying to determine the frequency components of overshoot and ringing on a fast rise/fall transient. If I have say a 10nS rise with some "hash" on the crest. Then expanding that portion of the wave can I assume the various full cycle transitions are the actual frequency components in my circuit ?
3. ## Simulating input bias current

Is it possible to simulate input bias current using the DC Bias analysis ? I tried but my simulation requires a voltage source. Can I fool the software ? I'm using 5spice. Want to simulate an LM358 with 1M across the + input, no signal in.... I'm new to Spice but not to op amps... Fredrick
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