Tag Archives: Diy

Dead Car Battery Recovery – Charging

Recover your dead car battery with a custom constant current / constant voltage power supply.
Visit http://diy.rednumberone.com
A regular charger will not charge a battery that was siting a long time and reached a very low voltage but this can!
After bringing it to normal voltage 10v to 12V, you can continue the charge with your regular car charger.



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UV LED Array Exposure Box DIY Build

Building a UV LED Array and a PCB exposure box out of cardboard.. yeah.

This UV LED Array and box pcb are DIY home built 🙂 with a simple design.

This exposes a PCB in 2,5 – 3 min using aproximately 1,2A at 12V

I use a 2A 15V power supply that powers a simple LM317T constant current module that keeps the LEDs from burning out.

Constant current is at about 1-1,2A, 12V.

R1 is 1 Ohm and at least 2W.


Led Current(I) = 1.25/ R1

Where 1.25 is the reference voltage of the LM317.

If you want to use the bellow PCB design, you are free to do so and if you want, please share this page 🙂

Right click and download the bellow 2 images, they are PNG – 1200dpi.

Top layer(single) for negative photo resist:

Solder mask – positive:
UV LED Array Solder Mask
Making the LED Array PCB:

The constant current module with everything built in a cardboard box. yes cardboard… 🙂