Strange Issue with 20A Raptor Build, need advice!

[werkkrew]

Hey All -

I recently completed a 20A Raptor build based on the below circuit diagram (drawn by me but most of the actual design was pulled from this forum).

It works great but has one very strange issue I can't figure out.

When I have my dual position voltmeter switch set to show output voltage, the switch LED turns on and the voltmeter displays a constant 3.00V of output.  The mod is not actually firing though.  When I fire it the voltmeter changes to display the actual output voltage as expected.

Can anyone see an issue with the circuit?  I thought maybe it was a wiring error but I did another build the exact same way and it has the same problem. 

Its not a huge deal as I can just run the mod most of the time with the voltmeter switch set to not display anything and only check output voltage when I need to but it bothers me.

Any feedback is greatly appreciated!

[Visus]

the switch LED turns on and the voltmeter displays a constant 3.00V of output.

if you have an led in the same circuit it will show that voltage.

[werkkrew]

But it shouldn't turn on.

When I used a very similar circuit with an OKL build it worked as intended. 

The way it should work is when I have the 3-way switch set to show output voltage the fire LED and Voltmeter should only turn on when the mod is fired but right now when I put the switch to show output voltage the fire switch LED and the voltmeter both come on, even when the mod is not firing.  When you fire the mod the voltmeter changes to reflect the correct voltage though.

[wa9w00d]

Does it still read and light with no atty mounted?  "cause I think I see a path from the pos. of the batt. through the fire led and res., through the atty, through the meter, and then to the neg. of the batt.

Wayne

[werkkrew]

Yes it does this even without an atty mounted.

[wa9w00d]

Well, if the wiring is as shown and both the led and meter are powered, then I would say that the current is flowing through the Raptor chip itself.  Just about got to be.  I don't know what that neg. sense line circuitry is like on the board, but that would be my next guess.

Wayne

P.S. Everybody loves build pics (hint,hint). 

[werkkrew]

Do you have any other examples of circuit diagrams which are for non-rated switches?  This diagram I made based on the ground side fire switch by Mamu, and added a couple of other components.

Here are some pictures/details of the builds: http://breaktru.com/smf/index.php/topic,1346.msg16600.html#msg16600

[wa9w00d]

Diagrams, me? Na, I'm new to this. Haven't even built a mod yet.  And when I do. I'll be stealing my ideas from folks like you, Breaktru, Mamu, Miskol (forgive I got that wrong), and too many more to name.  Those are some sweet mods, werkkrew. And I'm sure the batt. life is - shall we say, "sufficient". 

If you have a Raptor board left, you could breadboard the relevant part of the circuit, and prove or disprove my current path theory.  Maybe Craig or Breaktru could even tell you how to "fix" it.

Peace,
Wayne   

[Visus]

Take a picture of it you definitely have something wired wrong or was sent the wrong switch.

Ya like wayne said theres definite voltage going thru the reg if its showing on when it's off and you have a current path from your batts at your atomizer and the regulator output.  Be very cautious if you backfeed the batts with over 6v it may vent on you I would not use that mod until you get it sorted..

[werkkrew]

Ok let me summarize again what is happening:

When the 3-pos voltmeter switch is set to OFF the mod works 100% as intended.  Fires when I press the fire button, fire LED lights up, voltmeter is off.
When the 3-pos voltmeter switch is set to show battery voltage, it does, and nothing unexpected happens
When the 3-pos voltmeter switch is set to show output voltage, something strange happens.  The backlight on the LED lights up and the voltmeter comes on but the mod IS NOT FIRING.  When I press the fire button the voltmeter updates to reflect the actual output voltage and the mod fires as expected.

The only issue I am trying to resolve is why does the voltmeter come on when the mod is not firing.

[Visus]

 

That is strange indeed if it shows 3v how is it doing that?  There literally should be no way it should show that or have any voltage at all.  Theres something wired incorrectly. Looking at mamu's drawing that red arrow on the vmeter sw may confuse people.. did you attach ground to the switch and are feeding off the mosfet?  If so disconnect the ground and connect ground directly to the battery you are reading the fet and making the pfet partial open auto firing the mod but its too low to actually turn on the mod..   Makes sense now lol... IDK lol disregard,  I would rewire it and try again..

[wa9w00d]

OK, looked and thought about it some more.  I think I know were the problem is AND how to fix it.  That's a two wire meter, right? That's the way it's drawn.  That means the led's of the display are powered by the same leads that measure voltage.  So it is a medium impedance path, not high impedance like a real volt meter would be. that whole raptor section is sitting there floating on the positive of the batt. when the fire button is off.  When you connect that meter, current flows. Don't really matter exact path, it's THROUGH the meter.  Replace that two wire meter with a three wire, the meter part will become true high impedance, prob. solved!

Wayne

[wa9w00d]

Oh yeah, if I'm right, you can pretty much do away with the 3 position switch too.  Just use a double pole single throw. one set of contacts to power the meter, the other to connect it to the volt output of the chip.  If the meter is really high impedance, you will read very close to battery voltage when not firing, and applied voltage when firing.

Wayne