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Author Topic: Lidmotor's Penny circuit help needed.  (Read 52810 times)

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #75 on: October 02, 2013, 12:40:35 AM »
And I see you got your registration issue settled. Great!

I hope you don't mind if I still call it the DALM thing, though.
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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #76 on: October 02, 2013, 01:41:37 AM »
Still oscillating... collector peaks 1560-1580 mV at 490 kHz, 18 percent HI, battery voltage still 0.340 V.
Interestingly, the scope reports the "average" collector voltage as 340-350 mV.
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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #77 on: October 02, 2013, 01:50:26 AM »
IMPORTANT NOTICE:
I mistakenly had "0.340 mV" when I should have had 0.340 V, or 340 mV. I went back and corrected the earlier posts.... sorry if I had anyone all excited. Please calm down, if you thought I was running something on under a millivolt. Not yet! It's holding steady at 0.340 V, or 340 mV, which in itself is rather amazing. I'm starting to think it might be picking up some power from somewhere else.


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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #78 on: October 02, 2013, 10:22:18 PM »
Well, it is still oscillating, the voltage on the battery is now 334 mV, and the collector peaks are at 1260 mV, and the average collector voltage is about 340 mV.

So I am curious: this is the first time I've looked at the DSO's reported "average" voltages of the JT's spiky signal when the LEDs are not on but the thing is oscillating anyway. And I've noticed that the average collector voltage is nearly exactly the same as the supply battery voltage. Does this hold true for other JTs, I wonder? Do any of the JT researchers out there have any data on this question?

Meanwhile...

@ Shemp:  what happens in the sim if you "rotate" the transistor and hook it up incorrectly? That is, hook up the Collector of the transistor to the point in the circuit where the Emitter normally goes, and hook up the Emitter of the transistor to where the Base normally goes, and hook the Base of the transistor to where the Collector normally goes?
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Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #79 on: October 03, 2013, 02:16:41 AM »
Want me to remove the 1.2nF cap?

I am finding this amazing because it is still going and the voltage hasn't seemed to slip any.  Might not be powering any LEDs but for something to be running this long and the voltage hasn't budged smells funny but in a good way.

btw, it seems my notifications are on but I am not getting any which is odd so that is why I did not reply as quickly as normal.

With or without the 1.2nf cap it doesn't oscillate.
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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #80 on: October 03, 2013, 02:42:01 AM »
Well, with my build using the MPSA18 transistor, I decided to put the board together first without the 1.2 nF cap, although I have the board drilled for it. I was going to wait until I had baseline data without it, before installing on the board. But it gave ambiguous results when I had the thing in its first build, the "deadbug" construction. When I get the BC337 transistors I'll be able to test the 1.2 nF cap properly.

So yes, for the rotated transistor test, I didn't use the 1.2 nF cap.


It is still oscillating. The battery voltage is down to 334 mV, the collector peaks are 1320 mV and the frequency is 529 kHz. Scope reports "average" collector voltage 330-340 mV.


Do you have a 2sc710 in the sim?
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Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #81 on: October 03, 2013, 02:51:45 AM »
It does not but it does have the MPS line up (2sc/2sd are rare in it and I have had zero luck making my own even when I do exactly as it the tutorials say with datasheet in hand).

For it to have dropped only 3000 micro volts in this length of time it is hardly using any current to sustain its oscillation but I am surprised it is oscillating without a load too.
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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #82 on: October 03, 2013, 02:54:41 AM »
Sorry, I had the "rotation" test described wrong. But your schematic is wrong too! Your LEDs are now disconnected!
Please try the original circuit, but just hook the transistor as follows:

Base of transistor >  where the collector used to connect.
Emitter of transistor > leave in place
Collector of transistor > where the base used to connect.

So you just swap collector and base, don't change anything else from the original. Try with and without the 1.2 nF cap.
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Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #83 on: October 03, 2013, 02:57:21 AM »
Naw, my screenshot chopped off the ground but it was there only hidden.

Let me run up the new stuff you want.
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Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #84 on: October 03, 2013, 03:00:32 AM »
Same results with and without the cap.
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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #85 on: October 03, 2013, 03:10:36 AM »
Here's what I get:
First, "normal" orientation
Second, the "swapped" orientation: note the negative voltage excursions

It does this with the MPSA18, the 2sc710 and another thing called a "603" that I found many of in old TV chassis.
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Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #86 on: October 03, 2013, 03:15:56 AM »
I get nothing like that.
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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #87 on: October 03, 2013, 03:24:24 AM »
Hmm... of course I just realized the signal of the swapped config isn't the collector signal anymore it is the base signal. So if I move the probe, too, over to the bottom of the base resistor/capacitor...that is, still on the collector of the transistor, I get the "normal" signal again.



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TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #88 on: October 03, 2013, 03:26:44 AM »
Quote from: Legalizeshemp420 on October 03, 2013, 03:15:56 AM
I get nothing like that.

Well... hmmm.

Try lowering the input voltage back to 0.5 v
Try using the MPSA18 transistor, just to see if the sim will do what my hardware does

other than that I'm stumped.

My BC337 transistors will probably take a week to get here. They are supposedly coming from Colorado, we'll see, I guess.
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Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #89 on: October 03, 2013, 03:33:09 AM »
Quote from: TinselKoala on October 03, 2013, 03:26:44 AM
Well... hmmm.

Try lowering the input voltage back to 0.5 v
Try using the MPSA18 transistor, just to see if the sim will do what my hardware does

other than that I'm stumped.

My BC337 transistors will probably take a week to get here. They are supposedly coming from Colorado, we'll see, I guess.
I will tell you that with the circuit you see and changing the transistor (I did this a few times already) to a MPSA18 the BC337 blows it away.  MUCH higher peaks in both voltage and current and the MPSA18 would not do these 4 transistors with the 1.2V whereas the BC337 has no trouble in the sim.
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