Communications test, system bring-up

September 18, 2014



So, the hardware was finished and basically tested. Time to go for the software and get all this stuff to actually do something together. 🙂 I had to spend some time updating my motor “device driver” module to be compatible with Njay’s new power bridges. I took my “latest and greatest” version (which had been […]

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New wiring, power test

September 17, 2014


As usual, everything starts with a drawing. In this one I laid out the adapter board where I'll solder the cables to the plug that goes into the RasPi.

Vnevoa: Due to the new I²C communications bus scheme, I had to make new cables to connect the Raspberry Pi controller to Njay’s power bridge controllers. This cable is a simple “Y” shaped common bus made from CAT-5 network cable. The network cable is cool for the job because it’s already got 4 twisted pairs […]

I know why the drivers heat up

September 16, 2014


Modular FET driver board. It attaches to the power board via header pins.

Njay: I think I know what warms up more in the drivers. It must be the transistors that pull the N-FET up (to turn on), Q3 and Q8 in the schematics. When it’s ON, pumping current into the capacitor that is the MOSFET gate, is dissipates a lot of heat because it is being fed […]


Bridge supports crafted

September 15, 2014


A power bridge in its cradle

Njay got me not just the bridges but also some kind of ultralight plastic material plank to use as support for them. This mechanical support is of critical importance for the survival of the bridge circuits, because the only mechanical attachment between the bridges and their big heavy heat sinks are the electrical pins of […]

Power bridge status point & To-do list

September 14, 2014


Cool heat sinks

Njay: Status point, so that we both know where things stand. Both bridges have only 1 N-MOSFET connected, via a 100Ohm resistor. This is the configuration that tested the longest time, so I’m sticking with it. The gate resistor on the disconnected FET is removed (there is a pull-down that keeps the FET off). However […]


Christmas time!!!

September 13, 2014


NJay's power bridges, wrapped up with his customary love and care. ;)

NJay: Look what I brought you… Vnevoa: YESS!! 🙂 My turn to play with them!! 😀 And as soon as I got home I tried them out for size on the chassis… (to be continued…)

Power bridges ready. Or maybe not.

September 12, 2014


Njay's homebrew H-bridge power controller. You can see 3 boards: FET Driver board on the upper left, Microcontroller board on the bottom right, and MOSFET power board underneath them.

Njay: Hi, something happened. No, I didn’t burn the bridges. 🙂 But I goofed up again. Before handing them over to you I wanted to make a specific measurement now that I’ve got a 4 channel oscilloscope: to see the Vgs & Vds voltage wave forms in 2 parallel FETs. It’s a tough one to […]