hello, you need a back emf diode (reverse) between the +5v and the drain in order to protect the AO3400 from high voltage while turning off the fan
@onecircuit-as27 күн бұрын
@@amitmeyuhas6216 Good point - I’ll add it for the final version! 👍😀
@ColinMcCormack27 күн бұрын
Doesn't the mosfet body diode do that?
@BLOCKsignallingUK27 күн бұрын
@@ColinMcCormack The body diode allows current to flow in the direction from the ground rail to the drain of the mosfet. That's not what will happen when the mosfet turns off and the fan is still running. In that case, the fan motor negative lead will become more positive than the positive rail. A diode across the fan will prevent this voltage from rising significantly. A 1N4140 of 1N4001 would be fine.
@onecircuit-as27 күн бұрын
Diode installed (1N4001], leads shortened, all of it fits comfortably in the case.👍😀
@AndersNielsenAA27 күн бұрын
Fan should indeed be blowing on the heat sink :) Also - I’m happy to see it didn’t fry the GPIO when you hooked it straight to it in the beginning. I don’t think a Raspberry Pi would’ve been that forgiving with trying that much current. The internal reverse diode might be enough for back EMF?
@onecircuit-as27 күн бұрын
The fan is now blowing back into the case and I did install a flyback diode in the final version. 👍😀
@paulwojcik185627 күн бұрын
Hi, yes fan should blow onto heat sinks. The air flow when sucking comes via the least resistance path and so although will flow some air over heat sinks, most air movement will travel from sideways into the fan (as path of least resistance). Pushing the air onto the heat sinks will provide much moor cooling capacity as it will force air across the surface of the heat sink.
@onecircuit-as27 күн бұрын
Thanks Paul my thoughts as well! 👍😀
@ChrisSmith-tc4df21 күн бұрын
The BS170/2N7000 were really aimed at 5V gate drive switching applications, so their maximum gate threshold can be problematic unless one is hand testing and binning for lower threshold specimens. That combined with their lower transconductance can be problematic in 3.3V circuits - especially at colder temperatures.
@onecircuit-as21 күн бұрын
Yes I think the AO series looks like the goods for IoT logic level applications. 👍😀
@ChrisSmith-tc4df21 күн бұрын
@@onecircuit-as I thought so too, so 10 years ago I bought factory sealed 3000 each reels of AO3400A and its complement AO3401A. They only cost 4c each back then.
@onecircuit-as21 күн бұрын
@@ChrisSmith-tc4df Wow good pickup - I'm happy if I find 100 pcs relatively cheap!
@frankowalker466227 күн бұрын
I'd have the fan blowing into the case. But the size of those components gets me. I've read books with bigger full stops.
@onecircuit-as27 күн бұрын
I lost a few 603s along the way due to breathing. The fan is now blowing into the case, plus I installed a flyback diode and shortened the leads. 👍😀
@frankowalker466227 күн бұрын
@@onecircuit-as One sneeze and your project is gone. LOL Nice one. I did'nt think of the back EMF diode. 👍
@Steve_Coates25 күн бұрын
You can buy them in SOT-23 format which is much easier to solder.
@frankowalker466225 күн бұрын
@@Steve_Coates With my eyesight and tremors, SMD is just a myth. LOL.
@Steve_Coates24 күн бұрын
@@frankowalker4662 Join the club although on good days I can manage SOT-23.
@bonnome228 күн бұрын
I used this transistor for a 10 watt led. It's able to strobe at like 1mhz.
@onecircuit-as28 күн бұрын
Amazing little guy! 😮
@GnuReligion28 күн бұрын
Those Alpha-Omega 34xx series mosfets are ubiquitous!
@GnuReligion28 күн бұрын
Have you ever used an Airpax temp-activated passive switch? They have models that will close at 40C/50C/60C, etc.
@onecircuit-as28 күн бұрын
Interesting! I’ll look into that - thanks! 👍😀
@Rtube-b1l27 күн бұрын
It has all the right things to run a pulse laser except the watts is to low. If I use an arduino to create a PWM , need 75w 12v 2.5-30a . Any ideas how to drive a 75w 905nm pulse laser diode with an arduino ? Pulse Drvers cost upward of $1500.
@onecircuit-as27 күн бұрын
Use something like this circuit to trigger a larger fet like the IRFZ44?
@Rtube-b1l27 күн бұрын
@@onecircuit-as I will look at the data. I freaked myself out and got the laser diode to light up with a PWM and then I fried the PWM module. I tried with a Arduino and found that it is easy to use the simple blink code but I couldn’t get any light using a TIP31c. I might have killed the laser diode ? 4 days and nights of studying now , trying to get a 75w 12.8v 30a 100ns max pwm . I thought when I bought the diode for $20 it would be as easy as connecting to a buck converter not realising it needed a PWM. Thankyou for your quick reply.
@onecircuit-as27 күн бұрын
Good luck with the project, sounds like good fun! 👍😀
@Rtube-b1l27 күн бұрын
@@onecircuit-as I want to know how cheap I can drive a pulse laser diode ? The $2000 drivers look like cheap circuits so why are they so expensive ?
@onecircuit-as27 күн бұрын
🤷🏻♂️ This is often the case with electronics. Commercial WiFi extender AU$60. ESP8266 version? AU$1.50 😂