Mosfet Circuit

Mikebits

Well-Known Member

• Jul 1, 2010

• #21

You need a 10 k resistor from your clear pin to +5v otherwise the pin is in a unknown state. And AG is correct, you need to bypass your regulator.

 

I

ILikeComputers

Member

• Jul 2, 2010

• #22

Thanks so much
What do you mean by that to "bypass my regulator"?

Thanks
-ILikeComputers

 

audioguru

Well-Known Member

Most Helpful Member

• Jul 2, 2010

• #23

You should always look at the datasheet for an IC that you are using to see what additional parts are required.
Texas Instruments show a 0.33uF input bypass capacitor and a 0.1uf output bypass capacitor for their uA78xx regulators.

 

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• 78xx bypass capacitors.PNG

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ILikeComputers

Member

• Jul 2, 2010

• #24

Thanks
Would Simple 5V power supply work? I already have the parts for this.

Thanks so much
-ILikeComputers

 

Last edited: Jul 2, 2010

audioguru

Well-Known Member

Most Helpful Member

• Jul 2, 2010

• #25

ILikeComputers said:

Would Simple 5V power supply work? I already have the parts for this.

Click to expand...

It is the same circuit that you and I posted except its input capacitor value is higher and an additional 10uF output capacitor is added.

 

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ILikeComputers

Member

• Jul 2, 2010

• #26

Thank you everyone SOOOOOOO much.
Here is the final schematic I had.

-ILikeComputers

 

Attachments

• Schematic.png

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Last edited: Jul 2, 2010

Mikebits

Well-Known Member

• Jul 2, 2010

• #27

Just a few more changes. T1 base floats when pb switch is open. T1 needs a current limit resistor for base. The NAND gate inputs float when T2 is off. See my attached redmarks. Also I think AG mentioned that your laser diode needs a I-limit resistor, not sure so will let him comment on that.

 

Attachments

• unkcircuit.gif

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audioguru

Well-Known Member

Most Helpful Member

• Jul 2, 2010

• #28

T1 is an emitter-follower so it does not need a base current-limiting resistor.
The OP said in an earlier post that the laser diode has a built-in current-limiting resistor.

 

Mikebits

Well-Known Member

• Jul 2, 2010

• #29

audioguru said:

T1 is an emitter-follower so it does not need a base current-limiting resistor.
The OP said in an earlier post that the laser diode has a built-in current-limiting resistor.

Click to expand...

Okay, thanks for clearing that up

 

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ILikeComputers

Member

• Jul 3, 2010

• #30

How is this?

Thanks
-ILikeComputers

 

Attachments

• Schematic.png

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ILikeComputers

Member

• Jul 21, 2010

• #31

I have made some last minute changes to my circuit. Considering all of the mistakes I had my first time around, I figured I would post this just to make sure that it is correct.

Thanks
-ILikeComputers

 

Attachments

• Schematic.png

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