Hi all,

I'm still working on that PWM problem from last year and it has gone through many changes. However, what it seems I need to do now is regulate the voltage to my 555 and at the same time give the motor unregulated voltage. The circuit by itself, without a voltage regulator, seems to work great except for the mosfet getting really hot. But I haven't had any luck trying to add a 7805 to it. Quite honestly, I don't even know where to put it. I've tried the Vin, but I think I've just been grasping a straws.

If anyone could help, that would be fantastic! I'll attach a copy of my fritzing generated schematic after work.

 

The MOSFET gets hot? There may be a problem there. We'll wait for the schematic.

 

Ok, here it is without the 7805.

 

Is your mosfet a logic type?

Check this out, I just updated it. It might help.

http://forum.allaboutcircuits.com/showpost.php?p=117646&postcount=11

 

That can't possibly work the way you have it wired.

What is the "Power Plug" you show? I hope that's not to mains power! 12v-14v DC, perhaps?

You show a P-channel MOSFET, but it's oriented upside-down. You appear to be switching power to both the 555 timer and the motor. That's not going to work.

You show no values for your resistors, capacitors, or part numbers for the diodes. Please fill them in.

 

A 555 at 12 V will drive a MOSFET just fine by itself. A MOSFET should have a gate resistor.

You can cover the basics at the link I gave.

 

I apologize for the lack of labels on the diagram, I'll take care of that tonight. From the way it sounds though, I should take this back to formula. With that said, I did find this on the parallax forums and it seems to do something very similar to what I am trying:

http://forums.parallax.com/forums/default.aspx?f=36&m=369913

 

I've been trying for the last few days to partially breadboard the diagram in my previous post, but I'm not quite sure how to breadboard the ground. Does this just go back to the negative end of my power source?

 

I think I found my answer, it is the return path. So, in this example it would be the negative terminal of the power source, right?

 

Yes. All "grounds" should be connected together, and collectively connected to the negative terminal of your power source.

 

In your original schematic, in addition to the errors already noted, the diode appears to be the wrong way around, it will conduct all the time.....