Trying to make a simple LED blinker but it doesn't work...

[revv]

Im trying to copy this LED Blinker.

http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html

But I cant get it to work even tho I think I have everything connected together properly.

Im using two 9v batteries connected together so 18v total... but I think my problem might be because there is too much voltage?

When I connect everything together the LED lights up and stays on but doesn't blink.

This is from the website

"If the resistor that charges the capacitor is too low in value (or if the power supply voltage is too high), the current through the transistor will not become low enough for the transistor to turn off. If the resistor that charges the capacitor is too high in value (or the power supply voltage is too low), the capacitor will not be able to charge to a high enough voltage to enable the transistor to turn on. This is because the transistor draws as small amount of current before switching on."

Could the problem be as simple as there being too much voltage? I tried various resistors, I tried only using only 9v but then when I do that it doesn't even light up... and when I use 18v it stays lighted up.

 

[BobK]

Well, it does exactly what the paragraph you quoted says it will if the voltage is too high, so, I think yes. Why not try 12V. If you have a variable power supply, try that, varying it until you get it to blink.

Bob

 

[revv]

I don't have a variable power supply, but I do however have 1.5v batteries but I don't know if its possible to connect them to a 9v batterie I think I might have to just pass on this one until I get a variable power supply or something.

Thank you for the reply!

 

[Chemelec]

Use an LM317 to create a Simple Adjustable Power Supply.

Or you might just use 9 Volts and Reduce the 1k resistor to 820 Ohms.

 

[CDRIVE]

I don't have a variable power supply, but I do however have 1.5v batteries but I don't know if its possible to connect them to a 9v batterie I think I might have to just pass on this one until I get a variable power supply or something.

Thank you for the reply!

Yes, you can wire 1.5V cells in series with a 9V battery.

Chris

 

[hevans1944]

You can connect from one to twelve 1.5 V cells (AAA, AA, C, or D) in series to obtain 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, 13.5, 15, 16.5, 18 V DC. This works best with solid tinned copper wire, about 20 AWG or larger, connecting adjacent cells. Arrange the cells side-by-side with their ends alternating. Solder a short length of wire between adjacent cells at both ends in such a manner that all twelve cells are in series-aiding. Solder an alligator clip to two insulated wires and select whatever voltage you want from 1.5 V DC to 18 V DC by connecting across one to twelve of the series-connected cells. For a more compact layout, you can bundle the cells into a cylinder wrapped with electrical tape, half of the cells pointing one way and the other half pointing the other way. This makes it easier to solder on the inter-cell jumpers too.