Drawing too much power turns pic off ???

[Oznog]

Will 10nf do for the regulators capacitors?

Probably not. Look up the spec sheet for your specific reg, 0.1uF is common. 10nF is 10,000 times too small.

The motor capacitor and the input capacitor to the reg only needs to be done with one capacitor. Actually, there is little need for a capacitor on the motor at all.

It is impossible for the PIC to heat up at all in the way you shown. A MOSFET's gate draws no current. It is physically impossible to generate any heat with the driver unless you're driving it at many MHz. So the only answer is that resistor is far smaller than 10k, or something's not wired right on the PIC.

Are you sure that's a MOSFET? N-channel? And you have the gate/drain/source hooked up correctly?

But you can just take out the resistor and see. It's only there for two reasons. One, the PIC's got brief period when it turns on and when the power-on timer expires and the code sets the tristate bits. During that time, the transistor can turn on or worse, it can halfway turn on, which will dissipate a lot of heat in the transistor. Second, if the code's got bugs or has a power surge, the battery's run down, or whatever locks up the PIC, the state could persist indefinitely. That's why it's a good idea to guarantee the gate of a power MOSFET cannot float!

 

[williB]

That's why it's a good idea to guarantee the gate of a power MOSFET cannot float!

good point.

 

[TiagoSilva]

Assuming the motor isn't brushless , the zener was never the best option even because the voltage it mantains :lol: it starts there, any simple regulation circuit the 7805 should be more than enough to the motor i think that a transistor would be enough if it was built on a small heat sink, but if we have money to spend that's on you, i would stick to a simple regulated circuit made up with the very known 7805 and 2 Caps, to drive a small motor :lol: a darlington could be enough the mosfet is better but yet more expensive , if we have money to spend there is allways something better to use on it's just a mather of search and develop.

 

[TiagoSilva]

->

 

[GraveYard_Killer]

ohhh. that happened to me. using pic to power a 220V buzzer. whenever the pic turns on the NPN transistor, PIC stops working. after long months, this was resolved by putting a PC817 optocoupler for isolation instead of the NPN. now my circuit is working.

 

[williB]

->

that is a nice circuit.
what did you use?

 

[2camjohn]

Guys,

Its all working perfectly now.

Here is the circuit, make of it what you will. Im just happy its working and if it aint broke dont fix it!!!


Thanks to everyone who gave me advice :lol: , and sometimes told me im stupid :wink:


8)

 

[TiagoSilva]

I've used Protel DXP 2004 from Altium it's ratter expensive but everyone has it's own means of getting things, the whole studio is greater it have the Nexar wich alow u to design FPGA's they are very cool like the uP/uC's but more dificult to program and more expensive also but alows to ... check for yourself if you don't know allready ! 8)