computer Christmas lights

MrDEB

Well-Known Member

• Sep 10, 2022

• #41

will lower the resistor R1 to 1k
after looking over my schematic I discovered how to redo the power supply and drew a simplified one channel circuit.
I have too many terminal blocks. here is a simplified schematic.

 

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For The Popcorn

Well-Known Member

Most Helpful Member

• Sep 10, 2022

• #42

Power supply? If that means the voltage regulator, it looks exactly the same to me.... except the output of the regulator has no connection to the 5+ net.

 

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MrDEB

Well-Known Member

• Sep 11, 2022

• #43

I should have labeled it. In the connection manager, I added the 5+v to the output of the 7805.
I hover over the connection and it is connected. Maybe draw a wire connection from the 5volts pad to the 7805 output and hopefully, it will work Thanks.

 

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For The Popcorn

Well-Known Member

Most Helpful Member

• Sep 11, 2022

• #44

So points that aren't connected by lines and aren't shown as connected by net labels MIGHT be connected by magic? That's a recipe for disaster. It also means anybody looking at your schematics can't really know what's connected where.

 

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MrDEB

Well-Known Member

• Sep 12, 2022

• #45

I am aware and have incurred such disaster. Am going to just label he nets.

 

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MrDEB

Well-Known Member

• Sep 24, 2022

• #46

Proto-typed a MOSFET but it dosent work when applying 4.5-6 volts to the gate.
I have the battery pack (4.5-6v grounded to the 12 volt ground)
connect the battery to the gate but the led string fails to light. checked and rechecked.
here is data sheet for the mosfet https://www.jameco.com/Jameco/Products/ProdDS/209058.pdf
WHY??

 

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• MOSFET CONNECTIONS.png

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For The Popcorn

Well-Known Member

Most Helpful Member

• Sep 24, 2022

• #47

Does the LED string work if you connect it directly to 12v?

Do you have the mosfet flipped around?

Have you verified the mosfet # matches the data sheet?

 

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MrDEB

Well-Known Member

• Sep 24, 2022

• #48

YES
YES
YES NEED TO RECHECK THIS

 

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For The Popcorn

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• Sep 24, 2022

• #49

Yes is not an answer to question 2....or at least not a good answer.

Verify the connections, according to the orientation in the picture.

 

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MrDEB

Well-Known Member

• Sep 24, 2022

• #50

I did that several times thinking maybe I got something wrong.
All is correct as per schematic I posted.

 

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MrDEB

Well-Known Member

• Sep 24, 2022

• #51

It SHOULD work but not

 

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For The Popcorn

Well-Known Member

Most Helpful Member

• Sep 24, 2022

• #52

If you had it backwards, you probably fried it. The gate can only handle 10v.

 

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For The Popcorn

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• Sep 24, 2022

• #53

Make sure your resistors are in the right place. The gate resistor must be much smaller than the resistor to ground. They form a voltage divider.

 

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MrDEB

Well-Known Member

• Sep 24, 2022

• #54

I am using a battery pack for the GATE and a 12v power supply for the DRAIN/ LED.
NEVER TRIED APPLYING 12V TO GATE to let the magic smoke out.
The ground from the battery pack and power supply are connected together.
I have an 11k resistor connected to GATE and SOURCE. A 1.5k TO THE GATE

 

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For The Popcorn

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Most Helpful Member

• Sep 24, 2022

• #55

For The Popcorn said:

If you had it backwards, you probably fried it. The gate can only handle 10v.

Click to expand...

If you tried the mosfet both ways around, you had 12 volts on the gate.

If the circuit is truly as you say, either the mosfet is dead or it doesn't match the data sheet. Or physics doesn't work where you are.

 

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For The Popcorn

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• Sep 25, 2022

• #56

Did you figure out the problem?

 

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MrDEB

Well-Known Member

• Sep 25, 2022

• #57

BEEN COMPARING TO DATA SHEET
Looking at the part markings it says IRF520
I wondering if the data sheet is wrong?
going to swap the Drain and Source connections around?

 

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For The Popcorn

Well-Known Member

Most Helpful Member

• Sep 25, 2022

• #58

Try this, using a different mosfet and no resistors.

Where did you purchase the mosfets? Are you certain about the part number? The datasheet is not wrong.

 

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• Mosfet.jpg

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tumbleweed

Well-Known Member

Most Helpful Member

• Sep 25, 2022

• #59

MrDEB said:

Looking at the part markings it says IRF520

Click to expand...

Your schematic shows an IRL520. They're different parts... the IRF has a higher Vgs spec.

 

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For The Popcorn

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• Sep 25, 2022

• #60

Typos in part numbers are unforgivable.

 

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