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Author Topic: 3v OU Flashlight  (Read 563284 times)

verpies

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Re: 3v OU Flashlight
« Reply #150 on: April 23, 2014, 07:15:55 PM »
@Verpies, what do you see at Pin 12 of the hex inverter chip, the mosfet Gate? Can you take a scopeshot there?
I cannot because I did not build Akula's circuit.  The scopeshot is his.

conico

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Re: 3v OU Flashlight
« Reply #151 on: April 23, 2014, 07:17:06 PM »
 I have an HCF4069 and IRFZ44 didn't switch . Tomorow I will take an CD4069 and an IRF520-540.
 I believe you  didn't use the 100 ohm resistor and your irfz44 blown

TinselKoala

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Re: 3v OU Flashlight
« Reply #152 on: April 23, 2014, 08:31:26 PM »
I cannot because I did not build Akula's circuit.  The scopeshot is his.

Ah, OK, sorry, I thought you had built it. I was just wondering what the mosfet Gate drive signal looked like coming out of the inverter stage.




TinselKoala

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Re: 3v OU Flashlight
« Reply #153 on: April 23, 2014, 08:38:10 PM »
I really don't understand how the mosfet in this circuit is supposed to be switched. The inverter chip is only supplied with the 3 volts input power and the sine wave input is only a couple of volts p-p. How can the output of the inverter stage reach the 4.5 volt (approx) gate threshold voltage of a mosfet?



Grumage

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Re: 3v OU Flashlight
« Reply #154 on: April 23, 2014, 09:03:34 PM »
I really don't understand how the mosfet in this circuit is supposed to be switched. The inverter chip is only supplied with the 3 volts input power and the sine wave input is only a couple of volts p-p. How can the output of the inverter stage reach the 4.5 volt (approx) gate threshold voltage of a mosfet?

Dear Tinsel Koala.

As we have become very aware that deliberate errors are commonplace, could it be a humble Bi polar transistor ??  :)

Just a thought !!

Cheers Grum.

verpies

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Re: 3v OU Flashlight
« Reply #155 on: April 23, 2014, 09:09:18 PM »
I really don't understand how the mosfet in this circuit is supposed to be switched. The inverter chip is only supplied with the 3 volts input power and the sine wave input is only a couple of volts p-p. How can the output of the inverter stage reach the 4.5 volt (approx) gate threshold voltage of a mosfet?
Some MOSFETs have much lower VGS(TH) than 4.5V. 
For example the M8208 has a typical gate threshold voltage of 1.2V and as low as 0.5V.

gyulasun

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Re: 3v OU Flashlight
« Reply #156 on: April 23, 2014, 10:38:33 PM »
Yes,  the MOSFET family with low gate-source threshold voltage is called logic level gate type if you wish to search for them. Several manufacturers produce them.

Gyula

TinselKoala

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Re: 3v OU Flashlight
« Reply #157 on: April 24, 2014, 12:24:18 AM »
Well, maybe I'll be able to find a logic-level mosfet locally. Does anyone know the part number specified for the schematic?

Meanwhile I'm 95 percent finished with a build. I'm experimenting with a different construction technique than I usually use. I ordered 3 MC34063A chips for 3.99 US from an Ebay seller, they should be here in a couple of days. Saturday or Monday, probably. Still need a couple of resistors and a capacitor, which I'll get from my local supplier tomorrow. I've got an IRF3205 in there now even though I don't expect it to work. The wires are to the transformator which I haven't wound yet.




magpwr

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Re: 3v OU Flashlight
« Reply #158 on: April 24, 2014, 12:38:43 AM »
I really don't understand how the mosfet in this circuit is supposed to be switched. The inverter chip is only supplied with the 3 volts input power and the sine wave input is only a couple of volts p-p. How can the output of the inverter stage reach the 4.5 volt (approx) gate threshold voltage of a mosfet?

hi TinselKoala,

The fav 600volt mosfet 47N60C3 which i normally use in my experiment do have a gate turn on voltage threshold from 2volts...4volts for low current.For max current from mosfet gate plateau voltage is 5.5v.
Do check datasheet for your selected mosfet.

TinselKoala

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Re: 3v OU Flashlight
« Reply #159 on: April 24, 2014, 01:59:26 AM »
OK.... here's something of a teaser. I did get the mosfet to switch. See the scopeshot below.

I don't have the MC34063 or some other components on the "input" side, nor any coil yet. I'm just testing the inverter-mosfet "output" side to see if the inverter functions and drives the mosfet.

So I'm giving the board about a 3V supply to power the chip. And I'm using the Interstate Function Generator to inject a sine wave signal into the Pin 13, monitoring on the bottom trace of the scope. And I'm monitoring the mosfet Drain response on the top trace. Both traces are set to 2 v/div. The scopeshot shows one possible response waveform. But there are others! My setup is very sensitive to the input voltage to the board; a hair more than 3 volts and it works better, the mosfet will now turn fully on.... but with just a bit more, the mosfet then _stays_ fully on  100 percent .... impossible to explain in text really, so I shot a video, but it will be an hour or so before it's done processing and uploading. Meanwhile... the sinus signal to the inverter does result in a response at the mosfet, at least I know that much.

The nice square flat tops on the Drain trace are at the supply voltage and indicate the mosfet fully OFF.

verpies

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Re: 3v OU Flashlight
« Reply #160 on: April 24, 2014, 02:12:18 AM »
Meanwhile I'm 95 percent finished with a build. I'm experimenting with a different construction technique than I usually use.
That's nice!  Even suitable for high frequency signals. 
Did you cut grooves in that laminate with a milling cutter?

TinselKoala

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Re: 3v OU Flashlight
« Reply #161 on: April 24, 2014, 02:19:19 AM »
That's nice!  Even suitable for high frequency signals. 
Did you cut grooves in that laminate with a milling cutter?
Heh... .No, I used an Xacto miter box and a small hacksaw blade to cut the material. It's ordinary circuit board material. I cut some long skinny strips, then sawed slots thru the copper every 0.1 inch to make isolated segments or pads, then cut two 7-segment and two 4-segment bits from the strips and glued them to the baseboard with superglue to make the chip socket mounts. Then I positioned the "positive supply rail" strip along the top, and added 5 more little individual pads for the junction points. This turns out to be a very easy technique, and as you point out, the 100 percent ground plane and tight layout should help for HF .

verpies

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Re: 3v OU Flashlight
« Reply #162 on: April 24, 2014, 02:26:39 AM »
No, I used an Xacto miter box and a small hacksaw blade
...and I was thinking a milling machine or at least a Dremel tool for such precision work.  Nice "hack"saw job, anyway.

OK.... here's something of a teaser. I did get the mosfet to switch.
This might piss you off but I think I heard the Akula persona say that the entire CMOS Hex Inverter chip was disconnected while making this video.

You'd have to get a confirmation from a native Russian speaker, though.

TinselKoala

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Re: 3v OU Flashlight
« Reply #163 on: April 24, 2014, 03:15:20 AM »
...and I was thinking a milling machine or at least a Dremel tool for such precision work.  Nice "hack"saw job, anyway.
Thanks but it's really not that precise.... pads are different sizes, angles aren't right, edges aren't straight... it looks more precise than it actually is, I guess. Rough and ready...
Quote
This might piss you off but I think I heard the Akula persona say that the entire CMOS Hex Inverter chip was disconnected while making this video.

You'd have to get a confirmation from a native Russian speaker, though.
No, not pissed at all, I expect goalposts to move, designs to be changed, errors in schematics, etc. And I don't expect it to work at all, really, so if it does I'll be really happy and surprised.   ;)
I think that the DC-DC converter chip should light the LEDs at least, whether the output stage is there or not. But it will take me until next week to find out, probably. By then I expect at least two more new and different designs from Akula.

My video showing the effects I found so far is uploading now and should be ready in a few minutes:

 http://youtu.be/nJ1dyzst2Rc

I think that the inverter chip is really underdriven and underpowered, so it's behaving strangely.

TinselKoala

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Re: 3v OU Flashlight
« Reply #164 on: April 24, 2014, 04:10:16 AM »
Sorry I forgot to push the "publish" button. YouTube keeps improving, and improving, and improving....

http://www.youtube.com/watch?v=nJ1dyzst2Rc