Category Archives: Electronics - Page 24

More electronics

Posted by sm2wmv on March 31, 2012 Comments Off

I’ve been a busy boy and built a USB-dongle for the openASC bus. This dongle can be used to communicate straight out to the bus. I had a previous version of this that needed external 12v to be able to transmit, but I made a new version with improved bus filtering but the main new feature is a step up converted which makes 9v out of the 5v that the USB port supplies. That way it can operate on its own without an external DC supply.

I also did more work on the amplifier project. I mounted 2 pcs of small relay boards which will be used to switch the input filtering plus also the relays that switch the output PI-network of the amplifier. I found this to be the easiest way to solve the issue of switching 12/24v relays since the amplifier control board had ULN2003A drivers to drive these small 12v relays. I also soldered lots of cables, so now the control panel is hooked up to the micro controller and soon its time to actually start writing the code, not that much too do on the electronics. I need to add another relay board to be used to switch ON/OFF the amplifier, toggle HV etc. plus I will need to hook up the potentiometers used to position the capacitors of the PI-tank to the control board.

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All PCB info uploaded

Posted by sm2wmv on March 29, 2012 Comments Off

I have now uploaded all the information for the circuit boards that I do sell, so check it out!

http://www.sj2w.se/contest/?page_id=1511

More PA automation progress

Posted by sm2wmv on March 25, 2012 Comments Off

Today I spent about four hours in the lab fixing some stuff for the PA automation. I did solder cables with pull-ups and decoupling capacitors in the control box and also added connectors to those cables. I made sure to label them at once so that there are no mix ups in the future which might cause failures. I also soldered the cables for the 230v supply voltage for the three different switches power supplies and tested them, they seem to work fine. I also added a fuse for the 230v (2A). The stepper motor driver boards got 10v zener diodes to protect the driver MOSFETs. I used regular flyback diodes first but since they “consume” the same amount of current when turning the motors manually the motors had quite a lot of torque making it hard to turn them by hand. So with the 10v zener diodes that problems goes away and I can easily turn them by hand. Since the idea is to make the amp manually tunable and then just save the positions, they need to be easy to turn.

Some blurry pictures

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Electronic progress

Posted by sm2wmv on March 21, 2012 Comments Off

Last week I managed to finish the input filters for the amplifier. I did test them a bit and it seem to be working fine on 160-15m. I am not sure that I will be able to get it running well on 10m but we will see. Not that it will matter much since we don’t have any propagation on that band anymore.

Today I did some work attaching some cards and power supplies into the 19″ box which will be used to control the amplifier. Its got a control card, power meter and stepper driver card. The power supplies are switched ones for 24,12 and 5v. The last one is used for the stepper motors. There are a lot of D-SUB connectors, I added a few extra just in case for future improvements.

The idea is that the amplifier will be controlled from the openASC system. So when we change band in the shack the amplifier will tune itself automatically. At the beginning we will just have it preset-tuned but I might consider making it fully automatic in the future. The new power meter boards improved frequency counter makes it possible to automate the in-band tuning while I will use band data to control the band.