Timeline for Can I use 1N4148 diodes instead of a 1N4001 diode for reducing the speed of a 5V 1.8W fan?
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
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| Oct 5, 2018 at 14:35 | comment | added | D.A.S. | It's simple for DC muffin Fans because above stall speeds they are almost linear loads for "RPM/volt" . For quiet, compare fan in your hand vs next to a grill ( hear that?) next inside a "plenum", to avoid turbulence, then make as short as possible. still quiet ? and better inertial air flow. Any 1N400x will do, get a bunch, cheap | |
| Oct 5, 2018 at 8:52 | comment | added | Michel Keijzers | @TonyEErocketscientist Thanks for the comment, it seems it is more complicated than I thought, I will check all terms you mentioned to see the relation between them :-) | |
| Oct 4, 2018 at 23:23 | comment | added | sstobbe | The diode would survive a short term test, the 300 mA limit is based on the rise in junction temperature. At a 300 mA forward current the forward voltage of the diode is 1.2 VDC or more | |
| Oct 4, 2018 at 16:16 | comment | added | D.A.S. | You can gang a bunch of 1N4148’s together in xSyP arrays or get the right part or use BJT super bias | |
| Oct 4, 2018 at 15:56 | comment | added | D.A.S. | Fans use pretty efficient SMPS to commutate the phase current so their average rate VI load characteristics look like a variable resistor down towards stall speed only when SPINNING. So choose your % RPM above start Voltage or to decide on then choose V drop with power diodes... and by every means possible leave an optimal gap from fixed grill or heatfins to moving blade to reduce noise and then seal the gaps so air does not leak to keep it quieter from Eddy Current winds. Or the if want a thermistor to FET controlled fan speed, make one. With some BJT in between for gain and offset bias. | |
| Oct 4, 2018 at 15:39 | vote | accept | Michel Keijzers | ||
| Oct 4, 2018 at 15:07 | answer | added | Peter Bennett | timeline score: 10 | |
| Oct 4, 2018 at 14:48 | comment | added | Michel Keijzers | I have some 555's left, not 741's | |
| Oct 4, 2018 at 14:47 | comment | added | Finbarr | Nah, use a 741 to drive the fan | |
| Oct 4, 2018 at 14:46 | comment | added | awjlogan | How do you feel about a 555? | |
| Oct 4, 2018 at 14:42 | comment | added | Michel Keijzers | @awjlogan ok, clear (I want to connect it to a 5V source, I will than use another diode, hopefully I have some which are more suitable). I don't like PWM (no microcontroller involved). | |
| Oct 4, 2018 at 14:42 | answer | added | Tomomet | timeline score: 2 | |
| Oct 4, 2018 at 14:38 | answer | added | Dave Tweed | timeline score: 8 | |
| Oct 4, 2018 at 14:38 | history | edited | Michel Keijzers | CC BY-SA 4.0 |
edited title
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| Oct 4, 2018 at 14:38 | comment | added | awjlogan | The diodes are in series so have the same current through them, it's not split in two. Draw the circuit and see where the current loop is... Also, your fan may be 1.8 W at 5 V, but may well be different at 3V6. Better to use PWM anyway. | |
| Oct 4, 2018 at 14:34 | history | asked | Michel Keijzers | CC BY-SA 4.0 |