ne555 capacitor type

Thread Starter

incidentals

Joined May 3, 2020
3
I am looking to make a circuit from popsci.com called the pocket theremin. It is simply a free-running astable multivibrator with a frequency divider.

It requires a .01uf cap on the trigger of the astable, does this have to be an electrolytic or is there another technology that would do, it is just that I don't know if it needs to have a polarity. I think the symbol used says yes but a lot of the circuits online simply show a non-polar capacitor. They could all be wrong?

I am finding it difficult tracking down such a thing in through-hole devices and I am not sure about surface mounted devices.

theremin.png
Whole article here
 

Dodgydave

Joined Jun 22, 2012
9,169
Any polyester or ceramic capacitor will do, you will need a 1K resistor in series with both photo cells to prevent the 555 from being blown, on the discharge pin.
 

Hymie

Joined Mar 30, 2018
819
For the purposes of your circuit, the capacitor type will make no difference to the overall performance.
If using an electrolytic capacitor the negative terminal should be connected to the 0V of your circuit.
 

Thread Starter

incidentals

Joined May 3, 2020
3
Any polyester or ceramic capacitor will do, you will need a 1K resistor in series with both photo cells to prevent the 555 from being blown, on the discharge pin.
thanks for that... and especially the heads up about the photocells.
it is just so hard when you have nothing to mess with when your kit is out of reach during the lock down and having to buy everything from scratch.
 
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