T_G said:
First of all, I said 60 Euro. That is about 40 quid.
But if you can get a reliable working motor for a tenner, that's ok even though I think it will be more than that in the end. But let us know how you get on with this project, I would be very interested in seeing some pictures and details.
OK, I stand corrected, 40 quid then. However, since the rest of the system is also homebrew, I need to be able to programmatically control the dish position, and I'm not sure what the possibilities are with off-the-shelf systems (even if the cost sounds reasonable).
So far I've started on the first link, which is about a plug-in for VDR h**p://ventoso.org/luca/vdr/index.html. I looked at VDR but it seems it's not for me. I have a headless PC in the garage, so all my watching will be done over the ethernet. Currently I'm using dvbstream to send an RTP stream to mplayer on my laptop and that's working pretty well, unfortunately it's not particularly usable and it doesn't record, so I'll hack together some basic software to do that as well.
Some more details about the circuit (in case anyone is interested)
I already had a cheap dual-channel relay board off ebay, so I'll be using that for the driving part. The circuit is much the same as the one at ventoso.org, except it uses PNP transistors (Grrr... I hate PNP logic). Unfortunately it's also 6 volts, and I wasted a certain amount of time getting 6 volts from the PC power supply. Never mind.
I've wired up the pulse sensing circuit, and it seems to be reading the pulses from the actuator fine (putting 12 volts across the reed relay). I used a 40106BE (CMOS logic IC I had from >10 years ago) for the schmitt trigger, and an MOC3020 for the opto-isolator, which actually has triac output (overkill) but whatever. Otherwise, that circuit does seem to work. I'm surprised how slow the pulses are - I guess it doesn't have to be that accurate because wind blowing the dish introduces error anyhow. One thing I did add to the circuit was an LED to show the reed relay status, so I can clearly see when the dish is moving (the LED flashes with the pulses).
Next step will be to connect this pile of electronics to the parallel port and try to program it. The actuator draws about 2.5 amps, so I'm not sure right now whether I can get away with running off the PC supply or I'll have to have something else. Suspect I'll need some supply decoupling at the very least.
-biff
PS: I'll post a pic somewhere once I'm sure it works!