Posted on Feb 4, 2014

found out the hard way why the 6v EQ-5 hand controller should not be connected to 12v by accident. It only took, literally half a second to kill my hand controller. After some examination it became obvious that I had destroyed the large 40 pin micro controller, the `brains` of the handset. Upon further examination it became obvious that the controller has no form of either, overvoltage protection

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or reverse voltage protection. It doesn`t take much to kill that chip. So I thought, surely if the hand controller is that easy to destroy, a simple Google search would reveal a source of either replacement hand controllers or even better (thinking of the environment) just the programmed micro controller. It turns out that you have to buy the lot, at full price. The hand controller and steppers, everything! Well, I thought. there must be another way! And I am happy to say there is. Build your own hand controller. I could even protect it from over voltage, unlike the poxy standard chinese hand controller. The only down side was I had to learn to program a micro controller from scratch. Using a 555 timer circuit wasn`t an option because the stability of the 555 isn`t accurate enough. However a PIC micro controller running off a 4MHz crystal ought to be quite accurate. The image opposite is the hand controller I came up with. The project box and switches etcyou choose use are entirely up to you. I chose these because they are what I had to hand. The total cost to build the unit will be between £20 and £30 depending on where you source the parts. Over and above that, if you don`t already have one you will need an PIC programmer. I used the Velleman K8048 kit. This was a relatively cheap option but you have to build it yourself. Take a look at, the kit is available in the UK from and do a search for K8048. If you don`t want to...

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