I can not obtain a electrolytic cap 1.5uf 63V
I have 2 electrolytic 3uf 63V caps
If I connect the positive leg of one cap to the negative leg of the other cap . the uf reading from the other 2 legs is 1.5uf from the positive leg of one cap to negative leg of the other cap.
Is this correct. Can I do this as below.

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hi,
Yes, you can connect caps in series.

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Eric " Good enough is Perfect "
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If you are using electrolytic capacitors, you should know that their error is in general quite large and can be up to +40% of the marked value.

Unless your capacitor is used as a component that determines a certain frequency, in applications like oscillator or filters, there is no added advantage of using two capacitors in series if the purpose of the capacitor is simply for bypassing. In fact a single capacitor is often better than two in series.

You would need to tell us how the capacitor is to be used in circuit or simply show us the circuit.

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L.Chung

 

The Capacitors are used in a motor controller Circuit for a washing machine this Circuit has a TDA1085C Motor controller IC and a triac BT 137.
The + of one Cap goes to pin 4 of the IC
The + of the other Cap goes to pin 5 of the IC
There is a attachement of the chip layout.

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Could I use a 2 uf cap in the place of the 1.5 uf

 

The pin function of TDA1085C Pin4 and pin5 are "true speed" and "speed ramp" respectively.

Unfortunately this would mean a different capacitor value will alter the response of the circuit design. Larger capacitor value on pin4 will cause the "true speed signal" to appear smoother and thus can possibly slow down the speed regulation response of the control loop. But as 2uF or 2.2uF is just a little larger in value than 1.5uF, I would think the response will still be acceptable.

The value of capacitor on pin5 "speed ramp", together with another resistor, determine the slope of the ramp up/down of speed of the motor controller. Thus unless the resistor values are changed as well, the ramp rate will change too for different capacitor value.

So you are stuck with the existing capacitor design value on Pin5.

__________________
L.Chung

 

I can not obtain a cap 1.5uv 63V; so on pin 5 and 4 can I use the Caps in series for that operation.
The caps are not a prefered value.

 

hi,
Whats the voltage applied to the ic.?
I would not think its about 50V on pins 4 and 5 .???

There are lots of 1.5uF caps at 25Vwkg and 35Vwkg. look at digikey.

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Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
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Yes, 2.2uf can be used ,I've tried it successfully.

 

the last time i did that it worked. and i like to know why not.
by the way there is a trick to it i wander if you know this trick.

 

The more you post, the more everyone becomes aware you havn't got the faintest idea what you are talking about.!

The only trick I would like to know is how to make you disappear.!

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/