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Circuits

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DaOld Man:
I thought I would open a thread with circuits that are simple and may benefit us in our passion to re-create the Arcade experience.

First up is a simple circuit using a 555 and a handful of other components to control either DC motor speed (one direction only), or LED brightness.
LINK)

The circuit above is designed to control a motor, but if you replace the Q1 with your LED, it can control the brightness of the LED.
The 555 integrated circuit is a very common timer. (Available online or at Radio Shack).
The one rated for 4.5 to 16 volts is good for 200 MA.
If your LEDs draw more than that, just use a suitable NPN transistor to switch the power to the LEDs.
You can use the exact circuit in the link above, but just swap the motor in the circuit with your LED (with the appropriate resistor for your LEDs.) The diode around the motor in the above circuit is not needed, if you are controlling LEDs.

Got any useful circuits that you think would help out the group?
Post them here. We all need inspiration.

Edit: Here is the above pwm circuit, modified to control LED brightness:

pixel.arcade:
Very interesting, inspiration is a keyword!

DaOld Man:
Here is a very good H drive which is pretty easy to make.
This is not my circuit, it is posted here, with a lot of info on how to build it.
Caution! I highly suggest you use heat sinks on the power transistors, especially if you use PWM for speed control. I fried the transistors on my first build, without heat sinks.
The circuit:

ed12:
hi
interesting thread
i have always loved the 555
i did a google 1 day to find a 555 timer circuit
and came across 45 circuit's u build with 555
i did not book mark it but thought i would point it out

ed

DaOld Man:
Here is a very handy circuit I made a few years ago. Actually it is a modified wireless doorbell. Using a cheap battery powered door bell, I made an extension to my current doorbell.
I needed it for upstairs because i had a hard time hearing the doorbell (which is downstairs) when I was upstairs working on my projects.
It would have been a nightmare to route a wire from the downstairs chime to an upstairs one.
I could have but you know a lazy man comes up with an easier way to do the job.
Its a pretty simple circuit and works very good, providing that you remember to change the batteries in the chime part.
I removed the small 12 volt battery from the button that came with the wireless door chime. I made a small circuit that rectifies, filters, and regulates the AC from the downstairs door bell solenoid.
Then I taped the button to always be on.
When someone pushes the outside button by the door, the downstairs door bell rings and the wireless button is energized, sending a signal upstairs and ringing that one too.
The zener I used to regulate the power is 8.1 volts, it is what I had in my junk box at the time. It really needs to be 12 volts. The 8.1 volts decreased the distance of the remote chime, but it was ok for where I placed it.
The diagram below really sucks, (I couldnt find my original, this is copied off my blog site), if anyone is really interested in doing this, I will re-draw it better.

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