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Minimum Voltage For Capacitors

Sloan5556

Mar 8, 2015
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Mar 8, 2015
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I was wondering, is there is a minimum voltage to make capacitor work? I have been trying to make a blinking LED project without using a 555/556 timer or microcontroller. I have been trying a BC547 transistor with almost now success. I just got one to work tonight. I was trying the 4.5v battery pack that I have been using for the 555 timer blinking LED projects but it didn't work. The one I just got to work called for a 12v power supply and it's working. I am using the same 100uf, 25v capacitor I used in the 555 projects. I am new at all this so I don't understand completely how a capacitor works or a transistor.
 

Bluejets

Oct 5, 2014
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It's likely the so called 4.5v is not quite up to scratch.
Think you'll find a standard 555 is 4.5v minimum and you could be right on the no-go level.
If you want low voltage operation of the 555 go to the cmos version.
Be aware they are static vunerable though.

Show your circuit and named components as it is possible to not have to use a transistor with the 555 output.
 

Sloan5556

Mar 8, 2015
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Mar 8, 2015
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Here is a link to the video,
.

The components are, 3.3k resistor, 150ohm resistor, 100uf capacitor, BC547, LED.
 

AnalogKid

Jun 10, 2015
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The problem is not with the voltage across the capacitor. The problem is the voltage across the transistor.

This circuit is well known. Its operation is very dependent on the transistor's reverse-breakdown rating. With most small signal transistors, it will oscillate reliably with a 12 V supply. 9 V is iffy, and 6 V usually will not work.

Here is a link to the original page:


ak
 
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