Question about "turning on computer" without a case.

[purbeast0]

With a NPN, the initial state of pin 3 will be 0, which will result in inputs to XOR being and 0 which gives you 1 on the output of the XOR.
This in turn feeds the base of the transistor and make it go to on state, which allows 5V to flow to the XOR. At this point both input of the XOR are one, resulting in output of 0.

Shit. It's going to flick on again after cap drain. The circuit is wrong. I got to rethink. The temporary connection while maintaining power to the circuit is really tricky.

There is a reason a push button is easy xd.

Oh dang okay lol. Push button is easier but it isn't really user friendly for what I am trying to do at this point so I'm trying to not have to do that if possible.

I do appreciate all your help though! Hopefully you can figure it out lol.

 

[sdifox]

Oh dang okay lol. Push button is easier but it isn't really user friendly for what I am trying to do at this point so I'm trying to not have to do that if possible.

I do appreciate all your help though! Hopefully you can figure it out lol.

I might be over engineering lol.

Try this.

Feed power to both input of the XOR, but on one input put the resistor and capacitor. This in theory should delay that input by about a second, so the xor output should be 1 for a bout a second then go to 0.

 

[purbeast0]

I might be over engineering lol.

Try this.

Feed power to both input of the XOR, but on one input put the resistor and capacitor. This in theory should delay that input by about a second, so the xor output should be 1 for a bout a second then go to 0.

Still nothing.

I just tried power -> pin1

Then I did power -> capacitor -> resistor -> pin2

Then I had pin3 -> resistor -> led -> ground

And I had power and ground completing it and no dice.

Is there just a simple way I can test out the XOR gate?

I thought if I did power to pin1, nothing to pin2, then LED on pin3 (with resistor between) that it would light up the LED but that is not happening.

EDIT:

Could I be giving too much power with the 4 batteries? My multimeter says its like 6.5v and according to this spec sheet:

https://www.nteinc.com/specs/7400to7499/pdf/nte74LS86.pdf

It says max voltage is 5.25.

<-- total noob though so maybe this has nothing to do with it.

 

[purbeast0]

Okay I just tested the XOR gate by putting power to pin1, ground to pin2, and resistor -> LED on pin3 and that works. So I know the XOR gate is working at least.

 

[sdifox]

Okay I just tested the XOR gate by putting power to pin1, ground to pin2, and resistor -> LED on pin3 and that works. So I know the XOR gate is working at least.

Now try power to both pin 1 and 2.
That should not give power to pin 3

 

[purbeast0]

Now try power to both pin 1 and 2.

Light didn't come on (as expected) with power going to both pins directly.

 

[sdifox]

Light didn't come on (as expected) with power going to both pins directly.

Add two resistor and a capacitor to one of the inputs. Trying to delay power getting to pin 2.

Actually test the capacitor first.

Power to cap then to resistor and led.

 

[purbeast0]

Add two resistor and a capacitor to one of the inputs. Trying to delay power getting to pin 2.

Still doesn't turn on. I tried adding 3 resistors and same result, and tried capacitor in both polarity directions.

Just for more info, the caps are 100uf 25v, if that matters.

 

[purbeast0]

Could this not be working because even before the power gets through the caps/resistors to the pin, there is no ground hitting the pin before?

Because the XOR gate isn't working if I only have power going to pin1 and nothing to pin2. It needs power going to pin1 and ground to pin2.

In the case where I'm trying to delay power to pin2, before the power gets there, wouldn't pin1 have power and pin2 have nothing going to it, and not work kind of like when I was testing it out with nothing going to pin2?

EDIT:

Although now i'm a bit confused because if I have nothing on pin1 and ground on pin2 the XOR gate activates pin3. I assumed it wouldn't since pin1 had nothing on it.

 

[purbeast0]

Okay so I just had a little bit of success playing around with this but it's odd.

All I did was do ground -> capacitor (neg polarity on the ground side) -> pin1.

And when I do that, the light turns on for like 1/2 second and goes out.

However, when I try to make the circuit again, the light does not come on. It's like the gate is "stuck" off now or something. To get it to work again, I have to basically take the cap out of the circuit and go directly from ground -> pin1, then the light stays on the whole time, and if I put the cap back in line, it will do the same behavior where it's on for a 1/2 second and goes back out.

I also tried with a resistor inline and it did not work.

 

[sdifox]

Still doesn't turn on. I tried adding 3 resistors and same result, and tried capacitor in both polarity directions.

Just for more info, the caps are 100uf 25v, if that matters.

and if you connect the resistor and cap to pin 1 and pin 2 gets 5v? this is so weird. What is the exact part number on the XOR gate?

 

[purbeast0]

and if you connect the resistor and cap to pin 1 and pin 2 gets 5v? this is so weird. What is the exact part number on the XOR gate?

https://www.nteinc.com/specs/7400to7499/pdf/nte74LS86.pdf

Not sure if you saw my other replies too above, I made some kind of progress I think lol.

And just to be clear, I am doing the ground to the flat side of the batteries and the power to the top side of the batteries. Just wanted to clarify in case I misunderstood that part lol but I'm pretty sure positive = power and negative = ground.

 

[sdifox]

https://www.nteinc.com/specs/7400to7499/pdf/nte74LS86.pdf

Not sure if you saw my other replies too above, I made some kind of progress I think lol.

And just to be clear, I am doing the ground to the flat side of the batteries and the power to the top side of the batteries. Just wanted to clarify in case I misunderstood that part lol but I'm pretty sure positive = power and negative = ground.

draw a little diagram, I am not sure I understand what is happening lol. Sounds like you are close to a solution.

 

[purbeast0]

Here's a pic of what I have where the first time I do it, it seems to work.

And I just realized that if I flip the capacitor around polarity wise, that it works the next time and then won't work until I flip it around the other way.

 

[sdifox]

Here's a pic of what I have where the first time I do it, it seems to work.

And I just realized that if I flip the capacitor around polarity wise, that it works the next time and then won't work until I flip it around the other way.

leave it alone for a while without doing anything since the capacitor has to discharge.


Measure it like this to see of there are charges left

How to Measure Capacitance with a Digital Multimeter | Fluke

Learn how to use a digital multimeter to measure capacitance.

www.fluke.com

 

[purbeast0]

leave it alone for a while without doing anything since the capacitor has to discharge.


Measure it like this to see of there are charges left

How to Measure Capacitance with a Digital Multimeter | Fluke

Learn how to use a digital multimeter to measure capacitance.

www.fluke.com

Just had to run out for like 45 minutes and when I came back yeah it worked. Is there no way to force it to discharge when power is lost or something like that? I will take measurements in a bit after I get back from doing some other stuff.

 

[purbeast0]

leave it alone for a while without doing anything since the capacitor has to discharge.


Measure it like this to see of there are charges left

How to Measure Capacitance with a Digital Multimeter | Fluke

Learn how to use a digital multimeter to measure capacitance.

www.fluke.com

I just did it and then put it in my multimeter and it looks like it has around 1.2v left and I slowly see it going down by the thousandths in the multimeter.

And if I do it backwards, the reading is around -1.2v and it goes towards 0 slowly like the above instance.

Is there anyway to just force it to discharge after it loses power, or to not hold any charge after running the circuit?

 

[sdifox]

I just did it and then put it in my multimeter and it looks like it has around 1.2v left and I slowly see it going down by the thousandths in the multimeter.

And if I do it backwards, the reading is around -1.2v and it goes towards 0 slowly like the above instance.

Is there anyway to just force it to discharge after it loses power, or to not hold any charge after running the circuit?

Resistor after the capacitor in parallel and the other end of resistor to ground.

Cap -- pin 1 XOR
|
-------- resistor. ----- ground.


Silly editor keeps removing my spaces...

The wire to second path connects to output of cap.


I am trying to pipe a pool filter system here xd

 

[purbeast0]

Resistor after the capacitor in parallel and the other end of resistor to ground.

Cap -- pin 1 XOR
|
-------- resistor. ----- ground.


Silly editor keeps removing my spaces...

The wire to second path connects to output of cap.


I am trying to pipe a pool filter system here xd

I wasn't getting what you said and was about to say that, but when I quoted you here I saw what you meant about spacing and figured it out. And it looks like we're in business!

Thanks again man! I don't know if I will make the actual circuit tonight or not and try it on the real thing but I will post back when I do. So in theory, with this hooked up, when the motherboard gets power, it will basically jump the PWRSW as long as I have the PWR and GND hooked up to the right wires, right?

 

[sdifox]

I wasn't getting what you said and was about to say that, but when I quoted you here I saw what you meant about spacing and figured it out. And it looks like we're in business!

Thanks again man! I don't know if I will make the actual circuit tonight or not and try it on the real thing but I will post back when I do. So in theory, with this hooked up, when the motherboard gets power, it will basically jump the PWRSW as long as I have the PWR and GND hooked up to the right wires, right?

Yea, that was the idea. But you probably want to power the XOR chip from +5v line. Also, the signal line has lower amperage so it will be slower to switch off.


Ideally you will put a relay before that drain circuit branch. Just like the relay from main game board but it stays closed (on) when there is no power applied to the relay. That way when system has no power the cap is attached to the drain branch.


The ground on the cap draining branch should be to one of the grounds from the power supply and not back to the second power button pin.

 

[purbeast0]

Yea, that was the idea. But you probably want to power the XOR chip from +5v line. Also, the signal line has lower amperage so it will be slower to switch off.


Ideally you will put a relay before that drain circuit branch. Just like the relay from main game board but it stays closed (on) when there is no power applied to the relay. That way when system has no power the cap is attached to the drain branch.


The ground on the cap draining branch should be to one of the grounds from the power supply and not back to the second power button pin.

What is the reasoning for powering the XOR chip from the +5v instead of the power on the PWRSW first pin? Is it not as much power?

Also I did not realize it matters where the ground comes from. How come I shouldn't use the one on the the second pin of the PWRSW?

Is that additional relay necessary? Like if I don't wire it up will it be fine? I was assuming this was all going to just be from the 2 pins on the PWRSW.

According to the manual for the mobo, the pins on PWRSW are "PWR" and "Ground" so I am not sure what exactly "PWR" means voltage wise.

 

[sdifox]

What is the reasoning for powering the XOR chip from the +5v instead of the power on the PWRSW first pin? Is it not as much power?

Also I did not realize it matters where the ground comes from. How come I shouldn't use the one on the the second pin of the PWRSW?

Is that additional relay necessary? Like if I don't wire it up will it be fine? I was assuming this was all going to just be from the 2 pins on the PWRSW.

According to the manual for the mobo, the pins on PWRSW are "PWR" and "Ground" so I am not sure what exactly "PWR" means voltage wise.

It's five volt, you just need to complete the circuit basically. The computer is turned on when you short PWR and GRD pin. The moment you connect the xor chip to those pins you complete the circuit. So use those two pins as signal line, not power source.

You don't have to do the relay thing if you don't want to. It is just tidier and safer.

 

[purbeast0]

It's five volt, you just need to complete the circuit basically. The computer is turned on when you short PWR and GRD pin. The moment you connect the xor chip to those pins you complete the circuit. So use those two pins as signal line, not power source.

You don't have to do the relay thing if you don't want to. It is just tidier and safer.

Ooooh I think I see what you are saying.

So for ALL ground that I need on the circuit, keep that separate from pin2 on the signal line.

And then for powering the XOR chip (the only power I need in the circuit) keep that separate from the pin1 on the signal line?

If that is the case, I will create a molex connector that can connect to the HDD power connector on the PSU, and use that to connect to the circuit board, and plug it directly to the PSU connector. I think that will do what you are saying if I'm following right.

EDIT:

Do you recommend I try this out with an LED for pin2 once I have the real circuit hooked up to the board? Like just to be sure? Or at this point is it a waste to do that since I know it works?

 

[sdifox]

Ooooh I think I see what you are saying.

So for ALL ground that I need on the circuit, keep that separate from pin2 on the signal line.

And then for powering the XOR chip (the only power I need in the circuit) keep that separate from the pin1 on the signal line?

If that is the case, I will create a molex connector that can connect to the HDD power connector on the PSU, and use that to connect to the circuit board, and plug it directly to the PSU connector. I think that will do what you are saying if I'm following right.

EDIT:

Do you recommend I try this out with an LED for pin2 once I have the real circuit hooked up to the board? Like just to be sure? Or at this point is it a waste to do that since I know it works?

Always test first xd. Powering the xor chip is just to make it work, it is not part of the logic circuit.

 

[purbeast0]

Always test first xd. Powering the xor chip is just to make it work, it is not part of the logic circuit.

Gotcha.

I will post back when I do the real thing and let you know how it goes!

Thanks again for all of this help! It's been super educating and fun, and now I'm intrigued by this circuit stuff.