Flashlight Without Batteries--from the book, "Haywired"

Step 9 Attach jack to capacitor

Solder the red wire from the jack to the capacitor (+). Solder the black wire from the jack to capacitor (-). These wires form the path that will be used to charge the capacitors.

Comments

[LazarusTree]

This circuit seems potentially very dangerous to me. I think there needs to be at least one diode between the voltage input and the capacitors to limit electron flow in one direction and with a voltage rating less than the capacitors.

On what you have here, if you reverse the voltage and/or exceed the voltage rating on the caps and this is a potential bomb that will send shards of plastic flying everywhere.

[EngineeringShock]

If his input voltage is 3VDC, then he's not going to over-charge the caps. I'd be more concerned for the input source with no limiting resistors in series with the caps. That's a good way of destroying your wall wart,

[shobanaelango]

Are you suggesting that in any circuits it is better to use a diode between the voltage source and the capacitors? if we should add diodes to prevent from any accidents in a circuit in what all conditions and with what all components should we do that? It would be very kind of you to reply me............

[mrigsby]

If you choose to Use a diode, it should have a higher voltage rating than the capacitors and it should be able to handle as much current as your power supply provides. If you power supply has diodes on the output (and no capacitors beyond the diodes), then you probably don't need an additional diode. Although these capacitors store a lot of energy (for a capacitor), it's less energy than a "aaa" battery.

[shobanaelango]

Thank u very much for your response..... I have been doing a project on the topic RPS. So I made one. The specifications for it is (0-12)V. Since it is of variable type I used a LM317 regulator for it. The problem is I'm getting an output voltage range from (1.4-12)V but i should get from (0-12)V. After browsing thro' the Internet i found that diodes can be used in the circuit for that purpose but still, i don't know where to connect the diodes in the circuit to get the result........ I'm looking forward to your reply...........