September 2002

Saturday 7th September 2002

I bolted together one new MOSFET brick and started to wire it up. It was now looking quite solid and when I put it on the scales to see how it compared to the old bricks, I found it weighted exactly the same as two old bricks. However, the newer brick had the complete H-bridge driver on it rather than being split between two bricks on the old circuit, and the newer one was a lot more compact too. When I get it finished, I will try it out to see how it performs before I embark on cutting out the new parts for the second brick.


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Sunday 8th September 2002

I finished wiring up the MOSFET brick with wires and smoothing capacitors, and was then ready to test it out. I gingerly connected the brick to the left hand side drive of the old motor controller, and then attached a low powered motor to it. I didn't want to draw too much current to start with just in case there was a problem.

   

First time I tried it, the motor ran okay in one direction, but wouldn't go backwards. I wondered what the problem could be, but decided to try it on the right hand side drive before pulling things apart. Luckily it worked fine on this side, and I realized that the left hand side must have suffered a bit more damage that I thought during the Series 6 battles when I lost a drive and was grilled over the flame pit. When I was satisfied that the brick was working okay, I connected it to one of the winch motors and tried it again. To my delight it seemed to all work okay, and the bricks didn't get warm either. This means I can now happily continue with making another MOSFET brick for the other side now.


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Wednesday 25th September 2002

I got through on the phone to Brady from Norgren, and asked him if they would be willing to help me with the Hassocks Hog's new pneumatics. He said they would be happy to help, and he would get one of his field engineers to contact me. There were a couple of guys who had loads of experience in building pneumatic systems, and they should be able to advice me on components and strategies. To show that I was serious and had at least put some thought into the design, I sent them a diagram of what I was proposing to use.

Schematic of the Hogs proposed new  pneumatics

This would also give them some idea of what I wanted when they spoke to me next, so I will patiently wait for a phone call.


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Sunday 29th September 2002

I finished cutting out the aluminium plates for the second motor controller MOSFET brick. This time I took a lot of time and trouble to get the holes drilled as accurately as I could with my cheap and "not so" cheerful bench drill. The time paid off, and by the end of the day I had all the holes drilled, and the MOSFETs connected up to the bus bars. All that now remained was to connect the large smoothing capacitors, and then test the brick out.


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Last updated 17th October 2002