Hello. I have a cooler (12V - 0,28A). I want to connect this to ESP32 and i have a TIP41C for do it. What is the base resistor that i have to use ? Thanks.
Try about 100 Ohms.
From what I found, the EXP chip can put-out 40mA. With 3.5V and about half a volt across the transistor's base-emitter, 75 Ohms is 40mA.
100 Ohms is 30mA. The TIP41 has a worst-case (minimum) Hfe (current gain) of 15, so that's 450mA and it should saturate with a 280mA load.
Ok, I used two 220 ohm resistors in parallel, to reach 110 ohms. The fan tries to start but doesn't. The less resistance I put, the less it can start. When I connect the fan to direct 12V, it works.
Use a MOSFET, it only needs voltage not current. Be sure to get something with a Vgs of about 2.5V and at least 2 Amps, more is good. The higher it is rated the cooler it will be.
1 Like
Can you share a schematic?
Did you measure Vce?
If that us less than 1V the fan should run...
Use your existing schematic, change the emitter to source, collector to drain and base to gate. I am assuming your emitter is grounded.
Mosfet i have the IRF1010E
I was asking @T3rf for his schematic. I know this should be pretty straightforward but maybe his schematic is wrong... (high side switching...)
I do it but doesn't work with IRF1010E, with gate pin direct to pin 16 from ESP32. I will do a schematic.
That is a good part but I would not suggest using it here as it is specified at VGS(th) 3V, min 2V, max 4 V. It might work but but get something with the max around 3V. Here is the data sheet, look at figure 3. https://www.infineon.com/dgdl/Infineon-IRF1010E-DataSheet-v01_01-EN.pdf?fileId=5546d462533600a4015355da5fa41883
Works! Thank you so much. I'm simply a fan of this, I'm just learning, why did it happen? Why only the negative in the collector and emitter?
Before, your configuration was "emitter follower", which is legitimate, but its output was only 2.5V or so.
1 Like
NPN transistors should be low side switch... (also named open collector configuration...).
PNP transistors should be high side switch, but you will need a second NPN to control the PNP to protect your 3V3 device from the high voltage at the base of the PNP transistor.
That is why low side switch is often used...
I think you are confusing Vgs(th) with logic-level. The MOSFET needs to be logic level, and for a 3.3V microcontroller needs to be 3.3V logic level too. Vgs(th) will be less than 1V for such a device. Vgs(th) is the "fully off voltage", nothing to do with being on. Its one of the MOSFET specs you can ignore, like the current rating (use on-resistance and power dissipation instead)
1 Like
The threshold voltage, commonly abbreviated as Vāā or VGS, of a field-effect transistor is the minimum gate-to-source voltage that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency. Wikipedia
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.