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Thank you. But what about those controllers with transistors that are intended for PC fans? The proponents are actually not that savvy?PC fans are not classical DC motors. They're actually synchronous AC motors with integrated inverters. Some of those inverters accept a logic level PWM signal for speed control.
PC fans are not classical DC motors. They're actually synchronous AC motors with integrated inverters. Some of those inverters accept a logic level PWM signal for speed control.
Some older PC type fans are designed to be PWMed just like an actual DC motor. Or voltage modulated with a buck converter. Nowadays, logic level PWM is the recommended way as it gives the best control.Thank you. But what about those controllers with transistors that are intended for PC fans? The proponents are actually not that savvy?
Two more questions.
1. If a fan is going to operate at full speed, does it make sense to feed it with PWM signal at all?
2. Regardless of the above. If I'd like to disable the PWM signal, can I simply cut the 5V supply to the 555 PWM control circuit or is cutting off the PWM signal wire off using a switch the only option?
PC fans are not classical DC motors. They're actually synchronous AC motors with integrated inverters. Some of those inverters accept a logic level PWM signal for speed control.
This was a stupid question actually. 100% speed PWM signal is simply continuous ('a flatliner') so there's no difference between such state and e.g. the PWM cable cut out and PWM 555 module ripped out from the board. Anyway, I think having ON/OFF switches for every single fan is very useful.If your not going to use the PWM signal, then you realy don't need the 555 circuit, you can leave the PWM line not connected and the fan will run full speed.
Another question. PWM signal off, fan power on case is clear. The fan should go full speed. What about the opposite case? If I disconnect the power line from my fan, do I have to use a separate mechanism for disconnecting the power to the PWM signal generating circuit?
Thanks!Don't need to worry, its safe to have the PWM controller still at on state (powered), while the fan is totally off from it's power.
Of course this assumed that you're not using those rare and weird non standard industrial fans.
I have tested the circuit with several additional PWM fans:
fan/note
Noctua NF-A14 / stops below 15 deg of pot. angle
Corsair 120mm CF12S25M12AP (from H60, H60i) / 95% RPM is the lowest achievable RPM
SilentiumPC Fortis 2 / ?
SilentiumPC Zephyr / 100% RPM at 3/4 pot. rotation
So I either made a mistake in the circuit or the circuit is no universally compatible with all PWM fans.
Note:
The article mentions the single 555 timer based PWM circuit is incapable of commanding a full 100% RPM of a connected fan. For every single fan I've tested so far there was no perceivable difference in RPM between the PWM circuit set to max and PWM disconnected.
a1. Unlike the reference design from the article I've replaced one of the ceramic capacitors with an electrolytic one, solely due to availability problems.
What is the "kilo post thread"? You mean the multi-page thread on PWM here on the forums? Could you recommend any keywords?the NF-A14 should never stop spinning on any lowest pot position as the noctua stated themselves that the minimum RPM is 300 (+/- 20%)
you need to dig up infos on the "kilo post thread" to solved your issues.
I had no issue when dealing with any PC class fans, only few rare breeds of server fans giving me hard times... real hard, though
The value is exact. 0.1uF if I remember correctly.Tell us more about this, does the replacement has "similar" capacitance ?