Arduino project

I got a nifty idea of a universal device controller to use with the Arduino. It is gear towards test equipment but it could be used for other things.¬†When I say test equipment I’m talking about power supplies, function gen, and maybe even multimeters.
It doesn’t have to be fancy of a setup like a touch screen and I2C hardware but simple a simple LCD and push button switches.

My take on this will use the TVout Library so I can use one of my many 7inch LCDs I keep finding at thrift stores. A simple 4×4 keypad array will work fine and maybe even use a smaller or bigger keypad if needed. There are also a few libraries that use the analog pins of a Arduino to control a keypad via voltage dividers. The fun part is keeping the pin count down to leave for expansion or maybe use some 74HC595 8bit shift registers.

This will be used for my bench power supply and also I plan to build a Function Generator kit to modify as well. In an older post I modified a Voltmeter sketch that uses the TVout library and maybe with some code changes I could add other options and make something of a multimeter. Maybe I could modify a cheap handheld multimeter to use the controller.

So here is the specifications for this project.
TVout support for the video.
PWM to DAC converter to control analog signals.
Keypad controlled with analog pins to keep the digital freed up for more control options.
Relay control for controlling power sources such as AC or output supply from a DC supply.

I’m thinking if I should use a TIP122 Darlington transistor or a ULN2003 transistor array for the PWM to DAC control. I could use the 4n35 opto but I don’t have any in stock.


Building an case for my cheaper transistor tester

I have one of those cheap Chinese transistor tester kits. Today I decided it needs a case. I have a case from a CB radio that will work very well to house the tester. At the moment I have to use cardboard for the front bezel until I can get some plastic or a decent blade for the jigsaw to cut some sheet metal. I plan when finished to paint it to match the rest of my gear or I could keep it with the fake wood panel look.

To make this work I had to modify the circuit board a bit such as replacing the female header for the LCD to make pins so I can use a ribbon cable to extend the LCD. The tactile switch was also removed with some wire to extend the button to the front bezel. While I was at it I removed the brightness pot and put on a typical 1/2 watt 15k pot so I can mount it to the front bezel as well. I just hope after recalibration it will work properly. Right now it sees thins with a 2 ohm resistance.

As you can see I finished it. Some acrylic paint helped a lot on the cardboard bezel. Also recalibrating it worked well. It now rests under my scope.