# Thin film capacitor for voltage multiplier

I am designing a voltage multiplier with 5 to 10 stages. I have this circuit where I run a transformer at 450KHz and feed the output to the voltage multiplier. Is it a good idea to use thin film capacitor?

I have it lying around and also super cheap when compared to ceramic capacitors of same rating.

Name of the capacitor used(ECW-FG2J155Q1)

Lets say I am making a 10 stage voltage multiplier (Cockcroft-Walton half wave multiplier) which runs at 450KHz with 250V fed to the multiplier, I should be getting 5KV as output. Is this a good choice of capacitor? I am worried about the derating at higher frequencies.

• Why does your hyperlink anchor text say "Name of the capacitor used" instead of the name of the capacitor used? Jul 11 '20 at 10:46
• You are making some bad assumptions like 450kHz with 500V is a good idea and 1.5uF is a good load for that frequency. Go compare your transformer and source impedance to the impedance of the cap. What do you see? electronics.stackexchange.com/questions/475533/… Jul 11 '20 at 10:52
• I am unable to determine the transformer impedance as it is attached. It is driven by an H-bridge driver IC which gives a square wave output of 5V peak to peak. I think its a MAX13256 connected to a 5V 5A boost regulator. As for the impedance of the Capacitor, I am guessing that would be 0.2497 Ohm/cap (Calculated using 1/2x3.14xfxC) Since this is connected in series, a 10 stage would have 2.4Ohm on top cap and 2.4 ohm bottom cap. I think it might be a 12VA transformer. (Guess) Jul 11 '20 at 14:39

$$\color{red}{\boxed{\text{Answered before the OP changed the goalposts}}}$$

Lets say I am making a 5 stage voltage multiplier (Cockcroft-Walton half wave multiplier) which runs at 450KHz with 500V fed to the multiplier, I should be getting 5KV as output. Is this a good choice of capacitor?

If your output voltage is 5 kV and you have 5 stages in your Cockcroft-Walton multiplier, then each stage will need a capacitor rated to at least 1000 volts and preferably more like 1500 volts for some degree of reliability.

The capacitor you have linked to on Mouser (ECW-FG2J155Q1) is rated at 630 volts DC as per this table in the data sheet: -

It can't be expected to work with any recognized degree of reliability so, my advice is: -

$$\color{red}{\boxed{\text{Choose one with the correct voltage rating}}}$$

Or

$$\color{red}{\boxed{\text{Run with 10 stages minimum}}}$$

• I am sorry, I made a mistake, the transformer will be outputting 250V, then with the 10 stages,i should be getting 5KV. Sorry again! Jul 11 '20 at 13:56
• @Deadpool 10 stages and 250 volt input means 2500 volt output. I've had to amend my answer so that folk coming across this don't think I'm a fool and can't read. Don't disappoint me again (if you value any help you might get here). Jul 11 '20 at 14:55
• I am sorry, The 250V will be doubled in first stage and then multiplied in the in the further stages, no? imgur.com/a/XFmmHBn -> Pic of the circuit I simulated in eagle, thats why I had the idea of 250V after 10 stages gives me 5000V. Sorry again if i am wrong. I was just following the simulation. Of course, this is an ideal case of capacitor and diodes Jul 11 '20 at 15:15