KG8
29-06-2007, 06:30 AM
At the suggestion of a friend I decided to construct the PWM Dew Heater controller as per the IIS project found here.. http://www.iceinspace.com.au/index.php?id=63,285,0,0,1,0 and thought I would post up my experiences on it.
I used the the dicksmith $15, K3072 speed controller kit which is rated at 20Amps rather than the little one. A note here for those who may want to use this kit in the future. The kit has been discontinued by DSE but there are some left at the main distribution centre so if you think you will want one, order it now! I bought 2 myself. Also it pays to check the parts against the list before you get too settled in. The kit I used had one of the transistors wrong and I was glad to have had the second kit on hand. I still have drive back though, and swap the missing part over to have a good second kit.
I incorporated a meter, backlit by a superbright red led that I dimmed a bit with a 300ohm resistor. The meter came out of an old tape deck and I wired it to the output of the speed controller with a 20K ohm resister in series on one of its leads. I think the hardest part of the whole job was making the square hole in the box for this meter. I drilled holes, used a butane powered 'hot knife' to cut close to my marked square and then a file, slowly slowly, filing, checking to see if the meter fitted, filing filing...
I used a 4 socket RCA bulkhead mount instead on the 3 and intended to have the battery power plugging into one and the outputs from the other 3. But at the last minute I thought this might lead to a disaster if I accidently plugged up the wrong way so I wired the battery input directly through the box.
There is a regulator, a small 3pin component that goes onto the circuit board. It is there to smooth out 'spikes' from DC motors and is not needed for a heater control. I does drain about a volt though so on the advise of my tech brother I left this out and wired directly across the two outside holes in the circuit board it's legs would have gone through. Using a leg cut off a resistor and pusing its ends down through the holes. Nice to have a brother with 35 years professional experience in this stuff. All else was done according to the post above aside from the fact that I forgoed the cigarette lighter plug in favor of an RCA that fits into my power distribution box. I have always tried to wire my electronics like the plugouts on a computer, no two plugs alike unless they do the exact same task. This means I can never plug the wrong one into the wrong socket. I have used some DSE stick-on velcro strips I picked up to secure the control box to my powerbox so it will become one simple unit that I can place on a battery box under the tripod but still pull apart when I pack up. Simple squares pack a lot easier I have found.
I highly recommend this kit, it is cheap, handles high currents and is very conservative of your batteries.
Frank.
I used the the dicksmith $15, K3072 speed controller kit which is rated at 20Amps rather than the little one. A note here for those who may want to use this kit in the future. The kit has been discontinued by DSE but there are some left at the main distribution centre so if you think you will want one, order it now! I bought 2 myself. Also it pays to check the parts against the list before you get too settled in. The kit I used had one of the transistors wrong and I was glad to have had the second kit on hand. I still have drive back though, and swap the missing part over to have a good second kit.
I incorporated a meter, backlit by a superbright red led that I dimmed a bit with a 300ohm resistor. The meter came out of an old tape deck and I wired it to the output of the speed controller with a 20K ohm resister in series on one of its leads. I think the hardest part of the whole job was making the square hole in the box for this meter. I drilled holes, used a butane powered 'hot knife' to cut close to my marked square and then a file, slowly slowly, filing, checking to see if the meter fitted, filing filing...
I used a 4 socket RCA bulkhead mount instead on the 3 and intended to have the battery power plugging into one and the outputs from the other 3. But at the last minute I thought this might lead to a disaster if I accidently plugged up the wrong way so I wired the battery input directly through the box.
There is a regulator, a small 3pin component that goes onto the circuit board. It is there to smooth out 'spikes' from DC motors and is not needed for a heater control. I does drain about a volt though so on the advise of my tech brother I left this out and wired directly across the two outside holes in the circuit board it's legs would have gone through. Using a leg cut off a resistor and pusing its ends down through the holes. Nice to have a brother with 35 years professional experience in this stuff. All else was done according to the post above aside from the fact that I forgoed the cigarette lighter plug in favor of an RCA that fits into my power distribution box. I have always tried to wire my electronics like the plugouts on a computer, no two plugs alike unless they do the exact same task. This means I can never plug the wrong one into the wrong socket. I have used some DSE stick-on velcro strips I picked up to secure the control box to my powerbox so it will become one simple unit that I can place on a battery box under the tripod but still pull apart when I pack up. Simple squares pack a lot easier I have found.
I highly recommend this kit, it is cheap, handles high currents and is very conservative of your batteries.
Frank.