Beginner facing a problem

[foregp]

Hi,

I am a newbie to Electronics. I am stuck at following,

1.
I have a circuit

Battery -> Switch-> Capacitor -> LED.

When switch is on to complete (close) the circuit, Capacitor charges, meanwhile LED is flashing till capacitor is fully charged. The problem I am facing is that when I switch OFF the switch and turn it ON again LED does not flash because capacitor is still charged. I am unable to solve this (discharge the capacitor without losing the functionality of flashing LED only for a while when circuit is on).

I want to do above only using basic electronic components (Resistors, Transistors, Diodes)


2. Is there any electronic component like Transistor, which will pass the current if no voltage/current is given to base but will stop conducting if + or - voltage is given to base.


Thanks in anticipation, Eagerly waiting for replies.

 

[Harald Kapp]

Welcome to electronicspoint.

1) You need to provide a discharge path for the capacitor. For example like this circuit offers via the changeover switch:

2) What you're looking for is a so called depletion transistor (depletion MOSFET), e.g. BSP 135. It will conduct with Vgs=0V and will turn off for Vgs < -1.5V.