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| Aimtrak solenoid clicks soon as power is applied |
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| AndyWarne:
The issue is not the MOSFET specification, the 33N10 does not overheat and does turn fully off/on. The pull-down resistor is not needed as the MCU drives both high and low. The issue is most likely a rare failure of the output of the MCU rather than MOSFET or other issue. Although the cause might not be in this case, I have come across damage happening when the recoil power was connected with reversed polarity. |
| Titchgamer:
--- Quote from: AndyWarne on July 03, 2019, 06:32:54 pm --- The issue is not the MOSFET specification, the 33N10 does not overheat and does turn fully off/on. The pull-down resistor is not needed as the MCU drives both high and low. The issue is most likely a rare failure of the output of the MCU rather than MOSFET or other issue. Although the cause might not be in this case, I have come across damage happening when the recoil power was connected with reversed polarity. --- End quote --- Regarding PSU’s Andy, Can I make a suggestion to you to ship the guns with a PSU’s in future as I always thought it was a little odd not getting one with the kit. |
| meltman:
I disagree Andy, the MCU is putting out pulses every time I hit "test". I verified by putting an LED on it. How is it possible to drive a FET to full open when it wants a 10v gate and it's only getting ~5v? The datasheet of that FET shows that it is not fully "ON" in that configuration. There is a thermal fuse inside the solenoids that blows - rendering the solenoids useless unless you remove it - if you've experienced the "stuck on" scenario your solenoids probably blew this thermal fuse. |
| meltman:
Youtube of BEFORE swapping the FET, verifying MCU pulse for recoil with LED. Yes the 36v PSU was connected for this test. Youtube of AFTER swapping the FET and adding 10k pulldown. |
| AndyWarne:
If there were a design issue we would have a huge number of failures but we dont. I have never come across a failed MOSFET but it does appear this is the case in the video. The threshold voltage is less than 5V and the on difference between 5V and a higher voltage on the gate is very small. There is not a thermal fuse, its a trip which resets, or should do. Its possible it might not be able to withstand a sudden over-temp caused by a solenoid stuck on permanently though. The reason for not supplying PSUs is product liability especially in the USA, and also complxity of supplying the correct power cord etc. Also high shipping costs which the China suppliers are able to bypass with their subsidized postage. We have only experienced two issues with recoil on a very small number of guns which are: Breaks in the 2 power wires in the USB cable, where it exits the gun: Cured with a cable re-design (thicker outer sheath) and larger packing box such that the cable does not have to be tightly folded in packing. Machining marks on a conical section of the recoil plunger and the internal part of the solenoid which sometimes caused "hanging-up" of the plunger such that is does not spring back. Cured by correction to machining process. |
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