The 24v Papst Clamp fan got much closer to its final configuration tonight.
The previous buck/boost power supply I had mounted inside the aluminum C portion, smoked itself the day after installation. Not a huge disappointment, as it was incredibly inefficient powering the fan.
I have a 10 amp buck/boost power supply That has both voltage and current trimpots, these are 200K ohm, where other power supplies the trimpots were 10k or 50K ohm. Bourns does not make 200K 10 turn pots, nor 150k ohm either.
I wound up ordering a new old stock 150K ohm OHMITE single turn potentiometer. I like the box it came in.
One issue with all my previous speed controlled fans, is that when I'd turn the pot all the way down, and the fan stops well before the dial is all the way down. It takes a while to stop, and if one is merely trying to slow the fan as low as it can go, one has to be there to spin the dial to the right level, instead of just cranking it down and walking away. It is time consuming to dial the fans down to low speed without stopping.
It is likely not good for the fan to be fed 5 volts, when it will not start until it gets 7.8 volts. it would also waste battery power doing this, performing no work other than creating heat.
I ordered a 150K ohm pot, intending to add a 50k OHM trimpot inline, so instead of going to zero resistance turned all the way down the 150k pot would only lower as much as I have the 50K ohm trim pot set. 50K ohms runs the Papst fan at 8.xx something volts.
The papst fan will spin as low as 7.46 volts, but it will not start spinning on its own from a dead stop until 7.79 volts.
I dialed down the 50k ohm trimpot until the minimum voltage with Ohmite pot turned all the way down was 7.79 volts. Maximum voltage is then close to 29 volts with Ohmite pot turned all the way up.
If necessary, I can get lower fan speeds by dialing down the 50k trimpot with the jeweler's screwdriver, and I can get higher speeds than 29 by dialing it up.
But I don't want speeds much above than 29 volts, as amp draw increases significantly over 29v, without all that much extra fan speed, and the fan is rated to 30v.
I soldered a 50k ohm trimpot terminal, right to a terminal on the Ohmite potentiometer, and used some amazing goop and the third unused terminal on the potentiometer to hold it in place. So my Ohmite pot grew a trimpot wart.
Dual voltage potentiometers in series.
I got a 6 inch microphone gooseneck instead of the 16 or 18 inch one which could not support the weight of the Papst fan when horizontal.
The 10 amp buck/boost power supply has no issues when I spin the voltage dial quickly from 7.79 volts to 29, where as the 80w drok, would stall and display a fault on the voltmeter and the fan would slow to a stop. It would not restart until turned way back down, down then slowly raised back up.
The Ohmite pot, is actually only 140.7K ohms, not 150. This actually limits the voltage to 29, which is kind of perfect. If were 150K ohms then I could dial in voltages well north of 30. However, I could use the current pot to limit amps to 2.32 and it would then be incapable of exceeding 29 volts powering this fan.
I am quite happy with the function of this powerful clamp anywhere fan. I need some sort of fingerguard, on the face of the fan, and a way to support some airfilter material I will form into a column the circumference of the fan extending many inches behind it, for lots of surface area and minimal restriction to airflow. A round pleated car air filter or two of the correct diameter would also work nicely to filter out workshop dust, and should not affect airflow much at all.
I'll likely trim some excess aluminum, paint it black, mount the voltmeter somewhere highly visible but out of the way, and paint much of it black. The voltmeter is not really a requirement anymore though, since I can't exceed its safe speed range, low or high.
Before the recent assembly, I was running this power supply loose and using the jewelers screwdriver to adjust speedas its flow in the workshop was required. Somehow, perhaps I shorted something on the underside of the circuitboard, I blew the 10 amp glass fuse on the power supply. It's not an easy to replace fuse.
I used my insulated flag terminal dies inside my Anderson powerpole crimper, to make my own ATC fuse holder.
I was bummed the holes in the circuit board for the fuse, did not allow for thicker wire, but so be it, I'll not be passing 10 amps through this device anyway.
I put a 7.5amp fuse in it, while the supply is rated at 10 amps and the fan draws under 2.5 at 29v.
The fuse is easily accessed and replaced.
The Ohmite pot came with a locking nut to prevent spinning the shaft. The part of the shaft one could grasp, was only 1/8 inches thick. It did not come with a knob.
My old 12v mattress heating pad's adjustment knob basically fits perfectly, and has a locking set screw on the side.
The previous buck/boost power supply I had mounted inside the aluminum C portion, smoked itself the day after installation. Not a huge disappointment, as it was incredibly inefficient powering the fan.
I have a 10 amp buck/boost power supply That has both voltage and current trimpots, these are 200K ohm, where other power supplies the trimpots were 10k or 50K ohm. Bourns does not make 200K 10 turn pots, nor 150k ohm either.
I wound up ordering a new old stock 150K ohm OHMITE single turn potentiometer. I like the box it came in.
One issue with all my previous speed controlled fans, is that when I'd turn the pot all the way down, and the fan stops well before the dial is all the way down. It takes a while to stop, and if one is merely trying to slow the fan as low as it can go, one has to be there to spin the dial to the right level, instead of just cranking it down and walking away. It is time consuming to dial the fans down to low speed without stopping.
It is likely not good for the fan to be fed 5 volts, when it will not start until it gets 7.8 volts. it would also waste battery power doing this, performing no work other than creating heat.
I ordered a 150K ohm pot, intending to add a 50k OHM trimpot inline, so instead of going to zero resistance turned all the way down the 150k pot would only lower as much as I have the 50K ohm trim pot set. 50K ohms runs the Papst fan at 8.xx something volts.
The papst fan will spin as low as 7.46 volts, but it will not start spinning on its own from a dead stop until 7.79 volts.
I dialed down the 50k ohm trimpot until the minimum voltage with Ohmite pot turned all the way down was 7.79 volts. Maximum voltage is then close to 29 volts with Ohmite pot turned all the way up.
If necessary, I can get lower fan speeds by dialing down the 50k trimpot with the jeweler's screwdriver, and I can get higher speeds than 29 by dialing it up.
But I don't want speeds much above than 29 volts, as amp draw increases significantly over 29v, without all that much extra fan speed, and the fan is rated to 30v.
I soldered a 50k ohm trimpot terminal, right to a terminal on the Ohmite potentiometer, and used some amazing goop and the third unused terminal on the potentiometer to hold it in place. So my Ohmite pot grew a trimpot wart.
Dual voltage potentiometers in series.
I got a 6 inch microphone gooseneck instead of the 16 or 18 inch one which could not support the weight of the Papst fan when horizontal.
The 10 amp buck/boost power supply has no issues when I spin the voltage dial quickly from 7.79 volts to 29, where as the 80w drok, would stall and display a fault on the voltmeter and the fan would slow to a stop. It would not restart until turned way back down, down then slowly raised back up.
The Ohmite pot, is actually only 140.7K ohms, not 150. This actually limits the voltage to 29, which is kind of perfect. If were 150K ohms then I could dial in voltages well north of 30. However, I could use the current pot to limit amps to 2.32 and it would then be incapable of exceeding 29 volts powering this fan.
I am quite happy with the function of this powerful clamp anywhere fan. I need some sort of fingerguard, on the face of the fan, and a way to support some airfilter material I will form into a column the circumference of the fan extending many inches behind it, for lots of surface area and minimal restriction to airflow. A round pleated car air filter or two of the correct diameter would also work nicely to filter out workshop dust, and should not affect airflow much at all.
I'll likely trim some excess aluminum, paint it black, mount the voltmeter somewhere highly visible but out of the way, and paint much of it black. The voltmeter is not really a requirement anymore though, since I can't exceed its safe speed range, low or high.
Before the recent assembly, I was running this power supply loose and using the jewelers screwdriver to adjust speedas its flow in the workshop was required. Somehow, perhaps I shorted something on the underside of the circuitboard, I blew the 10 amp glass fuse on the power supply. It's not an easy to replace fuse.
I used my insulated flag terminal dies inside my Anderson powerpole crimper, to make my own ATC fuse holder.
I was bummed the holes in the circuit board for the fuse, did not allow for thicker wire, but so be it, I'll not be passing 10 amps through this device anyway.
I put a 7.5amp fuse in it, while the supply is rated at 10 amps and the fan draws under 2.5 at 29v.
The fuse is easily accessed and replaced.
The Ohmite pot came with a locking nut to prevent spinning the shaft. The part of the shaft one could grasp, was only 1/8 inches thick. It did not come with a knob.
My old 12v mattress heating pad's adjustment knob basically fits perfectly, and has a locking set screw on the side.
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