Designing a PWM to Analog mini board for fans
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Ok, here it is! First board mounted!
I have to recognize the accuracy of TINA TI simulation. It warned me about an inestability, but I wasn't sure if it was a simulation error or the real thing. Turned out it was the real thing, TINA TI even nailed the shape of the inestability checked with a real oscilloscope on the real circuit. Luckily, I already found that a capacitor fixed the inestability in TINA TI, and it worked too in real life:
It's a shame that such a cute board needs something that cluncky , but hey, that's what betatesting is for.
The good news is the circuit works very well, the output is very smooth, and roge fans work perfectly. PWM selector also works as expected, allowing active high/active low/open collector PWM. And although the opamp is supposed to work from 4.5V, I tested it as low as 3.3V and it still worked ok! And the output beautifully tracks Vin on the fly.
The response from PWM changing is as fast as "I can't measure it visually" (about 0.3 sec according to the simulation) .
So from now on, time to request betatest units, knowing they will need that extra capacitor. I have components to build 10 boards, and 14 bare pcb's.
Regarding cost, this is what I thought:
Just a bare board: 4€/piece
DIY kit (without headers/jumpers): 8€/kit
Fully assembled and tested (with optional headers/jumpers): 15€/piece
( + shipping costs).@ZipZap , @marcelorider , @fcwilt still interested in betatesting?
Once betatesting is completed, I'll modify the board with only SMD diode and a new smaller SMD capacitor, so the board will be a little bigger but cute again.
Comments?
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Some oscilloscope captures, all at 250Hz, 4V PWM, 12V Vin.
(Apologies for my function generator, is quite rubbish)99% PWM (oscilloscope can't detect duty cicle reliably)
75% PWM
50% PWM
25% PWM
1%PWM
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Sounds all swell to me.
I'm still in on beta-testing, i would like an assembled board (because of a missing hotair-gun...).
For the final version, i would like eight (8) non-assembled kits. -
Hey, happy to see it is working fine
I'm in for the beta testing, shot you a PM, let me know something as soon as you can to get my hands on it.You also need to include or build info regarding the jumpers to make it easier for people like myself
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To all betatesters: How is it going? Any comments yet?
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Still testing, should be ready tomorrow or wednesday.
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Bummer.
I have another circuit (@Egon-Net for the big fan), which should have a ripple around 30mV.
It shows me a ripple of 28V... i think my oscilloscope is not working right.I have a replacement in delivery, so i should be able to make all my desired measurements around the weekend. Sorry for the delay.
/Julien
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Well, I just mounted 8 PWM beta boards in my printer, two for each tool (one cold end, one part cooling)
I already connected 4 of them, and they work beautifully. I finally can control my stubborn fans! I'll make some more endurance test (to check temperatures in the long run) and wait for the betatesters to report, but there should be no problem for a final board run.
Still interested?
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Everything ready for the next batch of final boards!
Everyone who asked me for boards is already contacted for this batch. There are 23 boards finally requested, so I'll probably do a 25-board batch. Does anyone else need one before I place the orders to part suppliers?
I can also supply a STL/STEP file with the board and a basic box just in case you need
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@egon-net Out of interest. What would the cost be per board, delivered to the UK? Do you think they could be assembled with a fine tipped soldering iron, or only hot air?
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@nexxcat said in Designing a PWM to Analog mini board for fans:
@egon-net Out of interest. What would the cost be per board, delivered to the UK? Do you think they could be assembled with a fine tipped soldering iron, or only hot air?
Regarding cost, this is what I thought:
- Just a bare board: 4€/piece
- DIY kit (without headers/jumpers): 8€/kit
- Fully assembled and tested (with optional headers/jumpers): 15€/piece
- Shipping costs to UK: 5€
Regarding building the board with a fine soldering iron... It could be done since every part has its legs exposed and parts are not that small (SOIC8 & 0805 SMD), but it would be much more difficult.
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@egon-net Thanks
I'll hold off for now then, but great work on the product! -
This is the new board:
It's a bit bigger so now the capacitor is included and the diode and the led are in top side. Also a bit more of space surrounding the in/out connectors.
BTW, I think it's the last board I make with Ultiboard. I have tested Kicad and its support for footprints is way better (I can directly import them from Mouser!)
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@nexxcat said in Designing a PWM to Analog mini board for fans:
@egon-net Thanks
I'll hold off for now then, but great work on the product!Thanks!
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@nexxcat said in Designing a PWM to Analog mini board for fans:
Do you think they could be assembled with a fine tipped soldering iron, or only hot air?
You can practice with one of those Aliexpress kits https://www.aliexpress.com/item/1005002070994262.html . It's not that difficult once you get used to it, especially SOIC and 0805 packages which are relatively on the large side.
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@egon-net said in Designing a PWM to Analog mini board for fans:
BTW, I think it's the last board I make with Ultiboard.
Most likely Kicad will give you nicer 3D renderings.
Sometime people also post hard to find models on sites such as grabcad or gitbub.
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@zapta said in Designing a PWM to Analog mini board for fans:
@egon-net said in Designing a PWM to Analog mini board for fans:
BTW, I think it's the last board I make with Ultiboard.
Most likely Kicad will give you nicer 3D renderings.
In fact, Ultiboard renders are VERY ugly xDD. In 1998, when I started using it, it was like "wooha!". But now it's 2021, and it's the very same render
It's just that I can go from Multisim to Ultiboard comfortably, and Multisim has a powerful analog spice simulator which I use a lot. I'm trying to transition to TINA TI + KiCad. I wish KiCad had a good spice simulator!
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@egon-net said in Designing a PWM to Analog mini board for fans:
I'm trying to transition to TINA TI + KiCad
If paying for a subscription is an option for you, take a look at https://www.circuitlab.com/ . It has a more modern front end, works in a browser and has a cleaner user interface, and has nice feature such as sharing your schematic and simulation with others.
Most of my projects are digital so in the rare cases I need a simulator I use https://en.wikipedia.org/wiki/LTspice (free, powerful, dated user interface like most circuit simulators).
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@zapta said in Designing a PWM to Analog mini board for fans:
@egon-net said in Designing a PWM to Analog mini board for fans:
I'm trying to transition to TINA TI + KiCad
If paying for a subscription is an option for you, take a look at https://www.circuitlab.com/ . It has a more modern front end, works in a browser and has a cleaner user interface, and has nice feature such as sharing your schematic and simulation with others.
Most of my projects are digital so in the rare cases I need a simulator I use https://en.wikipedia.org/wiki/LTspice (free, powerful, dated user interface like most circuit simulators).
I'm trying to get used to TINA TI because it has most of TI spice models and it's fairly accurate (I do a lot of analog designs). Its transient analysis is the most accurate I've found to date. But thanks for the suggestions! I'll have a look
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25 board batch on its way!
- Parts ordered to Mouser
- Boards ordered to JLCPCB
Waiting...
- Parts ordered to Mouser
