Voltage Doubler using NE555 timer

cacophony · Post by **cacophony** » 09 Jul 2009, 13:05

Hi guys! I'm just wondering if this schematic I made through EAGLE CAD is the same as the one posted at http://www.elecfree.com/electronic/volt ... th-ic-555/

I find the schematic posted at the said website unclear enough.

Thanks.

Post by **modman** » 18 Jul 2009, 20:31

Also have a look here:
viewtopic.php?f=13&t=80&

JiM · Post by **JiM** » 19 Jul 2009, 10:37

There shall be no connection between C4 and the output voltage ! You're shorting it to Vcc, defeating the purpose of the circuit.
I agree it's not easy to see in the original schematic that there is NO dot where these wires cross ...

earthtonesaudio · Post by **earthtonesaudio** » 19 Jul 2009, 17:14

Ah! Good call, JiM. I glanced here earlier but failed to spot that! I agree, C4 should connect to the main supply only, not to the boosted voltage. It would be even better to show it directly across pins 1 and 8 of the 555, because it should be as close as possible to that IC in the board layout.
One more thing, it wouldn't hurt to add the typical .01u cap from pin 5 (CV) to ground.

cacophony · Post by **cacophony** » 23 Jul 2009, 10:17

earthtonesaudio wrote:Ah! Good call, JiM. I glanced here earlier but failed to spot that! I agree, C4 should connect to the main supply only, not to the boosted voltage. It would be even better to show it directly across pins 1 and 8 of the 555, because it should be as close as possible to that IC in the board layout.
One more thing, it wouldn't hurt to add the typical .01u cap from pin 5 (CV) to ground.

what does the 0.01 uf cap do to the timer?

earthtonesaudio · Post by **earthtonesaudio** » 23 Jul 2009, 11:41

Reduces noise/false triggering when using a bipolar 555. It may not be necessary, but it wouldn't hurt anything to include it.