To be deleted

[itsu]

yes, good call Itsu


the frequency does increase with 'no feedback' (and i think this is because in the feedback case, the f/b pulse increases the cycle duration whilst the coil collapse energy
performs work, charging the battery somewhat & lighting the feedback LED - in the 'no feedback' case the coil collapse energy dissipates wherever it can)
interesting about the resistor pot - after i used the pot to select a suitable operating drive level i replaced the pot with a fixed resistor

the elco behaviour seems reasonable -

with feedback, the elco is drained in 2 ways:
1) buffering the LEDs
2) completing the coil collapse current circuit back thro' the Feedback LED

without feedback, the elco is only drained as in 1) above


thanks
np

NP,

you mention: "in the 'no feedback' case the coil collapse energy dissipates wherever it can".

So that i should be able to measure, but up till now (temperature tests, current tests) i was not able to detect.
Perhaps i should check with the Spectrum Analyzer if the spectrum is more polluted without feedback.


Itsu

[itsu]

QUESTION:  Is the average supply current, Isupply, equal to the difference between the current drawn, Iin, and the feedback current, Ifb?

ANSWER:  Yes it is

SCOPE TEST:  measure Isupply at a mid-range voltage (3.75V)

(With Feedback)
signal cycle = 70.4kHz, full cycle = 14.1us

DC average, across 1 ohm CSR, using scope math from traces shown below

Isupply: 8.0mA 
(full cycle)

Ifb: -5.24mA  *   (4.7us / 14.1us) = -1.67mA  (averaged over full cycle)

Iin: 14.6mA * (9.4us / 14.1us) = 9.7mA  (averaged over full cycle)

Difference between Iin & Ifb = (9.7 - 1.67) = 8.03mA

NP,

i cannot confirm your above question as i did not record the average (mean) current.
My voltages and currents are in rms, and then you see that Isupply is almost Iin while Ifeedback is way more then the difference.

Itsu   

[nul-points]

you mention: "in the 'no feedback' case the coil collapse energy dissipates wherever it can".

So that i should be able to measure, but up till now (temperature tests, current tests) i was not able to detect.
Perhaps i should check with the Spectrum Analyzer if the spectrum is more polluted without feedback.

Itsu

hi Itsu
yes, i was thinking energy radiated away from the circuit - the waveform across a supply CSR with no feedback shows a burst of HF and also some LF oscillations

thanks
np

[nul-points]

i cannot confirm your above question as i did not record the average (mean) current.
My voltages and currents are in rms, and then you see that Isupply is almost Iin while Ifeedback is way more then the difference.

Itsu

that's ok, thanks Itsu - my general post about the average supply current was just provided as supporting evidence relating to the results from my circuit, for other interested viewers of the thread

thanks
np

[itsu]

NP,

i just redid the basic power measurements now including the average (mean) current through the severall paths.

Picture is probably to wide for the thread, but decreasing it would make it unreadable i guess.

I looked at the Spectrum with my SA, but only a very slight increase in overall bottom level in the first 33MHz
is noticed, no specific peaks or noise bands, both with or without feedback.

By the way, just to confirm, i remove the green led cathode from the plus rail to measure without feedback.


Itsu