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Make a Ghetto Simple LED Flasher :) Answered

No programming or 555 Timers are required for this incredibly simple project.
Using a pop can, a small motor, and 2 LEDs you can create an LED flasher.

Full write up: http://www.hacknmod.com/displayMOD.php?hack=630

Video:

Discussions

Nice make shift mechanical solution for eliminating the 555; here is an electronic example:

LED flasher xsistors.gif

Hmm. What are those two 100k resistor lines for? And shouldn't there really be diodes on those lines?

In Goodhart's schematic, the 100k resistors and the caps form the timing circuit, and the LEDs and 470 ohm resistors are the load switched. It's a classic "astable multivibrator", and there are numerous circuits on the net. This circuit was also the example used One of my EAGLE/PCB instructables, so there's one possible PCB layout published too.

I'm the kind of guy that doesn't like to buy things unless I'm really sure I will use them, so I finally decided to get an electronics book. I can follow the paths of current, but I just don't understand why those two resistor lines are there. I'd think at one point in the cycle, you'd be sending current back towards the +v source-- a no-no as I recall. Can you help me understand this?

Does this help any?
At any given time, one of the transistors is off and one is on. The capacitor connected to the base of the off transistor charges through the associated resistor until the transistor must turn on. That transistor turning on simultaneously turns off the other transistor and discharges it to GND via the transistor... It all makes sense except for getting to that "one on, one off" state, which you can take on faith as being due to minor differences in RCT characteristics.

yeah, i hate messing with all the extra parts (transistors, resistors, capacitors) so, i just figured there must be an easy way, and heck, there is.

One advantage of the electrical one is that you can substitute potentiometers for some of the resistors, and put in a varicap and with a twist here and there make them flash just as you would like :-)

. That is great. McGuyver ain't got nuthin' on Joe426.

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westfw

10 years ago

That's... clever, I guess. Looks like a motor from a CD mechanism; if you keep some of the gears attached, you can probably slow down your blink rate some more. I'm ... somewhat flabbergasted that "ghetto" and "redneck" would seem to apply somewhat equally to this ... hack.

yes, the motor is from a CD drive. Another way to slow down the spinning of the motor is simple to reduce the current to the motor. (throw in a resister between the cell battery and the motor). basically the only reason i did this project was to see if it was actually possible, and hey, it was.

Thats really cool. Nice job.