Testing the TK Tar Baby

[TinselKoala]

TK,

What is the current draw on your 555 circuit while the TB is oscillating?

PW

200 mA is not unusual, but in the "quiescent" mode with no or minimum oscillations it's a few tens of mA. The 555 gets hot, depending on operating mode, hence the heatsink.

I'm still not completely sure about this; there is massive potential for groundloops in this circuit and test arrangement.
Yesterday my _BNC probe connectors_ at the scope were heating up at one point... I realized the whole  system was actually getting its power from one probe's ground lead at the neg batt terminal, up to the scope, thru the connectors, to the other probe's ground lead, and down into the circuit, because I had forgotten to hook up the main power negative battery lead to the ammeter at the right place.

I'll be doing more measurements on this later on, but I've got to do some "real work" today so I won't get to it before late tonight.

ETA: OK, here's a quick measurement. The above values were without the Voltage Inverter feeding the clock. So by increasing the voltage on the supply to the clock, I could get the oscillations to grow larger and the system could draw more current.

Now I've inserted the Voltage Inverter, and still using a regulated supply, I can take the input to the Inverter up to 15 volts (as high as I dare for chip protection) and I get about 55 mA draw indicated on a good moving-coil meter in series with the regulated supply. This only gives me about 90  mA indicated on the main inline DMM ammeter at the main battery, and appears to produce only a little load heating. So the Inverter isn't allowing the required current to flow through the clock, apparently. I still get nice oscillations (in the negative gate pulse mode) but not of sufficient amplitude to allow much load heating, apparently. I've not yet taken current readings when the Inverter is powered by the most negative main battery. That will have to wait, I've got to get real here for a while.

[MileHigh]

Hey TK:

I only skimmed the recent postings because I am at work.  I saw your little capacitor-diode trick to get a negative output pulse.  I have to assume it does induce negative oscillation mode but it's a kludge.

I can suggest two possible 'clean' solutions for everyone to consider.  If you have a five battery set, then just put a sixth battery in series with the set to give you the -12 volts (or -6 volts if you want).  So you can run your 555 on ground and -12 (or -6) volts.  The only load on the sixth battery is to power the timer and support the current drain from the NERD circuit in negative oscillation mode.

The other solution is to purchase a real DC-to-DC converter with +12 volts in and -5 volts out.  As long as the DC-to-DC converter can power the 555 and support the current drain from the NERD circuit then you are fine.  Assuming a five battery set, then the "bottom" battery in the voltage stack would have an extra load on it, the DC-to-DC converter.

But then of course if the bottom battery drains then Rosemary has a "Get out of Jail Free" card that she can play about the double-load on the bottom battery.

Personally I would go with adding the extra battery and then just "ignore" that battery when you do the testing.  Then run the load testing with a light bulb and prove that the batteries actually discharge and then it's game over for the NERDs.

MileHigh

[picowatt]

MH,

I do not believe it is acceptable to ignore the current draw from whatever is used to bias on Q2.

Regardless of whether an FG or a 555 circuit, etc is used, something must provide the current necessary to bias Q2 on and if ignored, represents an error term in the final power calculations.

A pair of center-tapped batteries or an isolated DC to DC converter could be used to power the 555, but the current necessary to bias Q2 on has to come from somewhere.

Even with an efficient isolated DC to DC converter operating off the main battery string, the converter will have to draw both its quiescent current and the Q2 bias current from the batteries.  Without that current, Q2 cannot be biased on and the circuit will not oscillate. 

Personally, I would consider using an FG as OK, if its power contribution was both measured and calculated into the final power calculations.

PW   

[MileHigh]

TK:

A small addendum.  PW caught me on this one before.

Since the 555 is emulating the function generator, it also has to support the current sinking requirement of the function generator.  The 555 output stage might not be able to do that all by itself.   So you might need to a simple transistor arrangement to do that.

A good old NPN driven by the 555 timer with a 50-ohm resistor at the collector would emulate the function generator current sink.   In this case "high" from the 555 output would become "low" on the output.  We wouldn't want any Joit-inspired mass confusion again.  But I am only addressing one of the output polarities.

Here is where I will defer to you guys, the "EXPERTS," for the best transistor configuration to act as a buffer with a 50-ohm output impedance between the 555 output and the NERD circuit.  All that is getting a bit foggy for me!

Sadly in a way, the glory days of the discrete transistor are long gone.

MileHigh

[MileHigh]

PW:

Personally, I would consider using an FG as OK, if its power contribution was both measured and calculated into the final power calculations.

Indeed, I agree with you.  And I was composing my last posting as you were composing your posting.  The first go round when I forgot about the current draw requirements to bias the Q2 array I felt dumb, like I was slipping.

Like anything as you get older, if you don't exercise the brain cells, then they start to atrophy.  When I first looked at the free energy forums, it had already been 15+ years since I worked as an engineer.

MileHigh