if anyone out there has the book electronics for the evil genius, please help.
Im stuck on lesson 16 and my capacitor must not be filling up because my light only comes on while it is connected and doesn't stay.

I have 9 volts coming through a signal diode that can only come in and not out, then it connects in parallel to a 10 M Ohm resistor that grounds, a 1 uF
capacitor that grounds, and to two inputs in a 4011 quad nand gate circuit.
The power is supposed to, in parallel, connect and give power to both inputs
to give a voltage high, and to fill up the capacitor. Then when the power is off, the capacitor is supposed to slowly drain through the resistor while still keeping power supplied to both inputs. The problem seems to be that my capacitor is not filling up, but i checked it and tried many other capacitors to
no avail.

Any ideas?

 

When 9V is connected to the 10M resistor, the 1uF capacitor and the two inputs of the gate then the capacitor charges immediately to 9V. When they are disconnected from +9V but the gate is still powered then the capacitor slowly didcharges into the 10M resistor and the gate will remain turned on for about 5 seconds.

I think you did not have the gate still powered (you disconnected the battery from the circuit?). Then of course the light will turn off immediately.

The 1uF capacitor might be a polarized one and it won't work if it is connected backwards.
The diode is polarized and it won't work if it is connected backwards. A line on one end is the cathode end. It should connect to the 10M resistor, the 1uF capacitor and the two inputs of the gate.

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Uncle $crooge