Soldato
Great stuff.
Thanks for the update.
Thanks for the update.
PWM to Analog converter circuit
- Thread starter Tealc
- Start date
Amazing. Guess what arrived today.
Yes you got it, the B772 transistor.
Spent a little while messing around trying to figure out which resistors to use for Lo-Med-High.
With my High setting (2x510 ohm in parallel for 255 ohm) I found the resistors running to the switch to get pretty hot, that's because they are only 0.25W rated and I'm allowing 0.3W to pass through them. I will have to fix that. I'm thinking I might just go with 500 ohms, 1.5k and 3.2k as my settings. This'll allow for 0.4A, 0.2A and 0.1A of fans to work with good travel. That's capability to drive 2-4 fans, 1-2 fans and 1x <1500RPM fan down to 500-600RPM and up to near maximum speed.
The B772 gets mighty hot when I throw 0.5 Amps at it. It's only 6W total to the fans but the B772 needs to dissipate some of that energy as heat.
So I soldered a heatsink on it. I'm still using the little wires that I was throwing any PNP on I could find to test. Makes it easier to swap out.
You may wonder if that's actually a single brass picture hook but you'd be wrong, it's a heatsink, really it is.
It barely gets warm now. The transistor has very limited surface to dissipate heat so this superbly designed heatsink really works well. Better than I expected actually.
I've also run some further tests with FET to Transistor and there's really nothing in it. The FET does allow slightly lower bottom end speed but it's so close it's not worth messing about. S8050 all the way from here I think.
So I'm closer to finished now. I have everything I need apart from the selector switches and possibly a male 4 pin Molex peripheral connector or two to power everything if it's needed. I should have a few of them on old fan splitters and stuff that I can use.
Next few minutes I get to fiddle I will change the resistors to the switch and retest the ranges.
I will also redo the board so it's thinner and longer, and possibly populate the selector resistors on the PCB, rather than have them on the cable.
Yes you got it, the B772 transistor.
Spent a little while messing around trying to figure out which resistors to use for Lo-Med-High.
With my High setting (2x510 ohm in parallel for 255 ohm) I found the resistors running to the switch to get pretty hot, that's because they are only 0.25W rated and I'm allowing 0.3W to pass through them. I will have to fix that. I'm thinking I might just go with 500 ohms, 1.5k and 3.2k as my settings. This'll allow for 0.4A, 0.2A and 0.1A of fans to work with good travel. That's capability to drive 2-4 fans, 1-2 fans and 1x <1500RPM fan down to 500-600RPM and up to near maximum speed.
The B772 gets mighty hot when I throw 0.5 Amps at it. It's only 6W total to the fans but the B772 needs to dissipate some of that energy as heat.
So I soldered a heatsink on it. I'm still using the little wires that I was throwing any PNP on I could find to test. Makes it easier to swap out.
You may wonder if that's actually a single brass picture hook but you'd be wrong, it's a heatsink, really it is.
It barely gets warm now.
The transistor has very limited surface to dissipate heat so this superbly designed heatsink really works well. Better than I expected actually.I've also run some further tests with FET to Transistor and there's really nothing in it. The FET does allow slightly lower bottom end speed but it's so close it's not worth messing about. S8050 all the way from here I think.
So I'm closer to finished now. I have everything I need apart from the selector switches and possibly a male 4 pin Molex peripheral connector or two to power everything if it's needed. I should have a few of them on old fan splitters and stuff that I can use.
Next few minutes I get to fiddle I will change the resistors to the switch and retest the ranges.
I will also redo the board so it's thinner and longer, and possibly populate the selector resistors on the PCB, rather than have them on the cable.
Missed a day as we went off to Drayton Manor yesterday in the glorious sunshine.
Now back and I'm just not 100% sure about this switch idea. Choosing the right combinations resistor that affect the power handling is much trickier than I first thought and I might have to spread them out even more as I'm not quite getting low enough speed on the single fan setup, it goes from 12v down to 7v but I'd like it lower.
For simplicities sake the switch is much better than a potentiometer but you do lose that fine tuning option which I thought was awesome, but might be making things a touch complicated.
I think this is the problem trying to convert a digital signal into analog without a microcontroller. The end product will work, and can work really well, but the setup of the circuit in the first place needs a little thought and attention to balance as many eventualities as possible.
Phanteks went for a simple design that worked with their own fan and would probably work with many other fans just as well.
Will have to throw it on my PC later if I get a chance and see what the real world speed of the fans is going to be with it's current setup of 500 ohm, 1.5k and 2.2k and then maybe try and push it out to 1k, 2k & 4k or something.
Now back and I'm just not 100% sure about this switch idea. Choosing the right combinations resistor that affect the power handling is much trickier than I first thought and I might have to spread them out even more as I'm not quite getting low enough speed on the single fan setup, it goes from 12v down to 7v but I'd like it lower.
For simplicities sake the switch is much better than a potentiometer but you do lose that fine tuning option which I thought was awesome, but might be making things a touch complicated.
I think this is the problem trying to convert a digital signal into analog without a microcontroller. The end product will work, and can work really well, but the setup of the circuit in the first place needs a little thought and attention to balance as many eventualities as possible.
Phanteks went for a simple design that worked with their own fan and would probably work with many other fans just as well.
Will have to throw it on my PC later if I get a chance and see what the real world speed of the fans is going to be with it's current setup of 500 ohm, 1.5k and 2.2k and then maybe try and push it out to 1k, 2k & 4k or something.
A microcontroller is a small processor basically. You program it to do whatever function you require and it can control stuff on it's output. To be honest I assume it would be possible with one but lack the knowledge on how it would be done.
I've not fiddled with microcontrollers as of yet as I've been mainly looking at good old fashioned electronics with off the shelf ICs and transistors.
Microcontrollers cost a few quid each and then there's the cost of the development board and learning curve to use them. There's loads of them though. Maybe that's a job for another time.
A lot of the little electronics items we buy have microcontrollers of some kind but they are usually embedded and preprogrammed. Discrete microcontrollers you can buy are like a single chip that can do thousands of different tasks and range fron just a few pins to ones with a large footprint and dozens of outputs.
Anyway I've swapped the Low setting to 4.4k and the low speed on a single <1500 RPM fan is much improved.
So at the moment I can power 3-4 lowish speed fans and control from 95% or so right down to sub 500 RPM. I can power 1-2 fans with the same range in the middle setting. I can also power 1 fan (be it a 1000 or 1500 RPM) to the same range. I can go lower if desired but think that 500-600RPM should be low enough for just about anyone.
I've not fiddled with microcontrollers as of yet as I've been mainly looking at good old fashioned electronics with off the shelf ICs and transistors.
Microcontrollers cost a few quid each and then there's the cost of the development board and learning curve to use them. There's loads of them though. Maybe that's a job for another time.
A lot of the little electronics items we buy have microcontrollers of some kind but they are usually embedded and preprogrammed. Discrete microcontrollers you can buy are like a single chip that can do thousands of different tasks and range fron just a few pins to ones with a large footprint and dozens of outputs.
Anyway I've swapped the Low setting to 4.4k and the low speed on a single <1500 RPM fan is much improved.
So at the moment I can power 3-4 lowish speed fans and control from 95% or so right down to sub 500 RPM. I can power 1-2 fans with the same range in the middle setting. I can also power 1 fan (be it a 1000 or 1500 RPM) to the same range. I can go lower if desired but think that 500-600RPM should be low enough for just about anyone.
So I deciced to try and mount the components on a smaller footprint of stripboard as already mentioned. I managed to get it down to 18x5 instead of 17 x 7 for a reduction of 20 odd percent. I also managed to get the switch reduction resistors mounted in a spare bit of space. For a final build (I cracked this board so will have to redo) I will use hot glue to insulate the upright resistors.
Terminating the 4 pin PWM connector terminals was a breeze with a pointy nose pliers, a soldering iron and solder. Safe and strong connection.
No heatsink as yet fitted to the B772. I will do a high load test on it tomorrow at low and high duty cycle to monitor the temperature as the change to 500 ohm has limited the current it now handles a bit.
A 3/4 pin header to mate with a 3 pin fan. I might just snip off the spare.
A close up of the selector switch. I will have this sticking out under the covering heatshrink and use a combination of a cable tie and perhaps hot glue to hold in place.
Hopefully tomorrow/next day I will do a demosnstration of how the switch works and how one would set it up for different fans.
Terminating the 4 pin PWM connector terminals was a breeze with a pointy nose pliers, a soldering iron and solder. Safe and strong connection.
No heatsink as yet fitted to the B772. I will do a high load test on it tomorrow at low and high duty cycle to monitor the temperature as the change to 500 ohm has limited the current it now handles a bit.
A 3/4 pin header to mate with a 3 pin fan. I might just snip off the spare.
A close up of the selector switch. I will have this sticking out under the covering heatshrink and use a combination of a cable tie and perhaps hot glue to hold in place.
Hopefully tomorrow/next day I will do a demosnstration of how the switch works and how one would set it up for different fans.
Soldato
Absolute magic.
Right guys as promised here's a video of me setting up for a few different fans by changing the switch position.
Simple enough I think.
Not totally happy with the High setting so even though I did record some video setting up three and four fans I've sinced modified it again to give just a tad more power differential betwen High and Medium. More on that soon.
So what you basically have is a choice to make on which setting you have it on, whether you want fast speed, low speed or a combination and compromise between the two. Regardless of this compromise though it is a lot more flexible than the Phanteks circuit. I still prefer the unlimited setting of the potentiometer but you are so limited then by the current capability of 0.1W through it.
I didn't test high load today and whether the B772 needs a heatsink but will do that soon.
Oh and I got the switches. They are bigger than the Tri-cool one but not a big problem. They also have mounting holes and solder holes so should be stronger.
Oh and I got these things today
Couldn't resist testing down the shed with a few fans.
I'm going to review it and test it and then switch the LEDs to orange
Simple enough I think.
Not totally happy with the High setting so even though I did record some video setting up three and four fans I've sinced modified it again to give just a tad more power differential betwen High and Medium. More on that soon.
So what you basically have is a choice to make on which setting you have it on, whether you want fast speed, low speed or a combination and compromise between the two. Regardless of this compromise though it is a lot more flexible than the Phanteks circuit. I still prefer the unlimited setting of the potentiometer but you are so limited then by the current capability of 0.1W through it.
I didn't test high load today and whether the B772 needs a heatsink but will do that soon.
Oh and I got the switches. They are bigger than the Tri-cool one but not a big problem. They also have mounting holes and solder holes so should be stronger.
Oh and I got these things today
Couldn't resist testing down the shed with a few fans.
I'm going to review it and test it and then switch the LEDs to orange
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Argh.
I think I might have to switch back to the FET BS170 as the S8050 transistor just can't work such a good range from low to high duty cycle as the FET. I've got a few BS170 and a few more 2N7000 which are similar but with slightly lower current rating, which shouldn't be an issue. Will have to check that out.
I think I might have to switch back to the FET BS170 as the S8050 transistor just can't work such a good range from low to high duty cycle as the FET. I've got a few BS170 and a few more 2N7000 which are similar but with slightly lower current rating, which shouldn't be an issue. Will have to check that out.
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Yes mate it's just got complicated trying to accomodate different fans and quantities.
Doing a straight single 0.12A fan or similar converter would be child's play.
Anyway the 2N7000 is similar enough to the BS170 and responds exactly the same as expected so I have plenty of parts. Response is so much better using a FET.
So as it stands I have a circuit that works well on 0.1A-0.3A of a combination of fans, which covers pretty much anything besides fans that go above 2500rpm. If you were to load on a 5000rpm 120mm fan it would just run slow on every setting. It would still work of course.
So to do...
1) High load 100% test. Will check transistors for excess heat.
2) High load 5% test. Will check transistors for excess heat.
3) Long time run test. I will leave it for a few hours chugging away and see how hot stuff gets.
Then if that goes well I will put together a final build and test on my PC.
Then once I'm happy maybe someone else would like to test one out.
Doing a straight single 0.12A fan or similar converter would be child's play.
Anyway the 2N7000 is similar enough to the BS170 and responds exactly the same as expected so I have plenty of parts. Response is so much better using a FET.
So as it stands I have a circuit that works well on 0.1A-0.3A of a combination of fans, which covers pretty much anything besides fans that go above 2500rpm. If you were to load on a 5000rpm 120mm fan it would just run slow on every setting. It would still work of course.
So to do...
1) High load 100% test. Will check transistors for excess heat.
2) High load 5% test. Will check transistors for excess heat.
3) Long time run test. I will leave it for a few hours chugging away and see how hot stuff gets.
Then if that goes well I will put together a final build and test on my PC.
Then once I'm happy maybe someone else would like to test one out.
Yes mate it's just got complicated trying to accomodate different fans and quantities.
So as it stands I have a circuit that works well on 0.1A-0.3A of a combination of fans, which covers pretty much anything besides fans that go above 2500rpm. If you were to load on a 5000rpm 120mm fan it would just run slow on every setting. It would still work of course.
So that means my funky red housing / orange bladed thingys that spin 2500rpm rated .60amp won't work on your converter?
Cus if I use them on my cooler they may need some rpm adjustment to balance out with my other fan.
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Ah but the TY-143 you refer to already use TY-143 goodness by design so they'd never come near my converter anyway
I of course can make one to work with much higher loads but it won't then work too well with lighter loads. Combining a high load fan with a low load fan would be ok though.
Most I've actually had working was in excess of 0.6A and that's just with the 1/4w resistors I have. With a power resistor or a resistor array I could drive up to 2A I'd imagine. I have loads of fans but doubt even together they'd go up to 2A.
Update: I managed to get it up to 0.75A on my old circuit with a bunch of resistors in parallel to share the load and got 5 fans spinning between 11.5v and 2.7v, which was nice.
Now running heat test with 0.37A at full speed on the final circuit with a slightly modified heastink (I cut the bottom hook off as there's no room for it now) as the B772 was getting quite hot. Ideally the circuit should be good for 0.3A with minimal voltage drop enabling powering of 1 high power fan, 2 or 3 low power fans.
It's trivial to increase the power output of the circuit by swapping a few resistors in and out, and even replacing the switch with just a single bank of resistors to give one high end power range. As these are hand made I can easily custom build power output to suit any needs. For example if I wanted to control a 0.08A fan such as a Gentle typhoon I would choose a 3.5k resistor. If I wanted to control a 140mm Spectre Pro I would go with 2k. A 120 Spectre pro would be 1k and 3 Spectre 1000RPM fans would need something around 750 ohms. So you see it's not really complicated to design the converter to control a known load.
I of course can make one to work with much higher loads but it won't then work too well with lighter loads. Combining a high load fan with a low load fan would be ok though.
Most I've actually had working was in excess of 0.6A and that's just with the 1/4w resistors I have. With a power resistor or a resistor array I could drive up to 2A I'd imagine. I have loads of fans but doubt even together they'd go up to 2A.
Update: I managed to get it up to 0.75A on my old circuit with a bunch of resistors in parallel to share the load and got 5 fans spinning between 11.5v and 2.7v, which was nice.
Now running heat test with 0.37A at full speed on the final circuit with a slightly modified heastink (I cut the bottom hook off as there's no room for it now) as the B772 was getting quite hot. Ideally the circuit should be good for 0.3A with minimal voltage drop enabling powering of 1 high power fan, 2 or 3 low power fans.
It's trivial to increase the power output of the circuit by swapping a few resistors in and out, and even replacing the switch with just a single bank of resistors to give one high end power range. As these are hand made I can easily custom build power output to suit any needs. For example if I wanted to control a 0.08A fan such as a Gentle typhoon I would choose a 3.5k resistor. If I wanted to control a 140mm Spectre Pro I would go with 2k. A 120 Spectre pro would be 1k and 3 Spectre 1000RPM fans would need something around 750 ohms. So you see it's not really complicated to design the converter to control a known load.
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So I did some long test with the sort of final board
The FET is mounted underneath as it's easier to swap it in and out when it's not hole mounted.
So that's just fine.
Next up is bringing it in the house and connecting it up to my graphics card PWM so I can change the duty cycle at a whim.
The FET is mounted underneath as it's easier to swap it in and out when it's not hole mounted.
So that's just fine.
Next up is bringing it in the house and connecting it up to my graphics card PWM so I can change the duty cycle at a whim.
This isn't hard work it's fun, or at least it is for me. Plus the wife has gone out for the afternoon so I get lots of time to tinker.
Brought a few fans and the circuit indoors to run on my PC as a final test before making a final final build.
The circuit has no effect on the PC as it sits purely on an output. My graphics card PWM signal was happy to go into the circuit and it had no effect on my graphics card fan. The circuit works exactly the same as it does off my bench power supply, although it does get 12v in my PC versus 12.3v on my bench power supply.
Fan speeds were good when the selector switch was in the correct position for the fans attached, giving me almost full 12v speed at the top end and sub 400 at 20% duty cycle. Even with four fans loaded up all fans would spin at 20% if they were encouraged, although I would say it was a bit overloaded and could really do with being just 3 fans.
I did notice during the test that one fan, a 120mm black Bitfenix Spectre Pro did make some bearing noise which I hadn't noticed before. It seemed to make it throughout the range of speeds so I checked it on a decent DC source and confirmed that it just didn't like being mounted horizontally.
Anyway another video of the PC test here. None of these are professional as you may have noticed but I feel it's easier to describe something with video than it is with just images and text.
Plus the wife has gone out for the afternoon so I get lots of time to tinker.Brought a few fans and the circuit indoors to run on my PC as a final test before making a final final build.
The circuit has no effect on the PC as it sits purely on an output. My graphics card PWM signal was happy to go into the circuit and it had no effect on my graphics card fan. The circuit works exactly the same as it does off my bench power supply, although it does get 12v in my PC versus 12.3v on my bench power supply.
Fan speeds were good when the selector switch was in the correct position for the fans attached, giving me almost full 12v speed at the top end and sub 400 at 20% duty cycle. Even with four fans loaded up all fans would spin at 20% if they were encouraged, although I would say it was a bit overloaded and could really do with being just 3 fans.
I did notice during the test that one fan, a 120mm black Bitfenix Spectre Pro did make some bearing noise which I hadn't noticed before. It seemed to make it throughout the range of speeds so I checked it on a decent DC source and confirmed that it just didn't like being mounted horizontally.
Anyway another video of the PC test here. None of these are professional as you may have noticed but I feel it's easier to describe something with video than it is with just images and text.