Too much of the shutdown circuit is hidden behind the ribbon cable. I haven't figured out the role of the two 220uF electrolytics that might be connected pos-to-pos.
No harm in that
My interest in a servo FE is to eliminate the degeneration resistor altogether and more importantly, the associated capacitor bypass so that we get no low frequency roll off. Your variation looks interesting and I suspect has a nice, slow startup characteristic as the opto output transistor bypass caps charge up.
One question though, given that you have eliminated the pots, how do you adjust the DC offset?
yup , startup , regarding voltages and currents in FE , is slow and nice , but not because of optos ...... charge of caps in drains (parallel to optos) is limited with JFets Idss and opto bjt isn't even conducting until caps are charged(enough)
credit ...... not certainly mine
solution is result of utter and shameless thievery
ZD25 power-up power-down waveforms
Today I made some measurements of my ZD25, which is similar to the XA25. The measurements were:
Today I made some measurements of my ZD25, which is similar to the XA25. The measurements were:
- CH1 (yellow): VF+
- CH4 Violet: Drive+
- CH2 Cyan: Drive-
- CH3 Pink: Vout
- CH4-CH2 Blue: Drive+ - Drive-
- Complete power-up and power-down sequence at 5 secs/div
- Power-up pulse at 0.5 secs/div
- Power-down pulse at 1 secs/div.
Attachments
I've not considered power off behaviour either, how serious an issue in practice do you think this is likely to be? If you have an amplifier already built then isn't it worth trying with a cheap loudspeaker?
Has there been any discussion of the shutdown circuit? I don't recall reading anything mentioning SCRs but I may have missed it.
Has there been any discussion of the shutdown circuit? I don't recall reading anything mentioning SCRs but I may have missed it.
SCR used in overhystericoutputcurrent protection
10A I believe , though - Papa relaxed triggering somewhat in latest amp iteration, according to his words
I have a feeling that , if amp is not making trouble during startup , it'll behave when sent to sleep ....... I mean - at least this one
10A I believe , though - Papa relaxed triggering somewhat in latest amp iteration, according to his words
I have a feeling that , if amp is not making trouble during startup , it'll behave when sent to sleep ....... I mean - at least this one
I'm confused.
What do we actually know about this shutdown mechanism? For example, does it limit the current to 10A, shutdown but reset automatically, shutdown requiring a manual restart or something else? Useful to understand the function before trying to analyse the mechanism. Again, not saying we need this in our own amplifiers, more a matter of interest.
What do we actually know about this shutdown mechanism? For example, does it limit the current to 10A, shutdown but reset automatically, shutdown requiring a manual restart or something else? Useful to understand the function before trying to analyse the mechanism. Again, not saying we need this in our own amplifiers, more a matter of interest.
My apologies, you are correct:
"it will protect itself by shutting off any channel which outputs more than 10 amps (200 watts peak into 2 ohms). The protection circuit is reset by turning the amp off for a few moments and then turning it back on."
Teach me to skim rather than read properly!
"it will protect itself by shutting off any channel which outputs more than 10 amps (200 watts peak into 2 ohms). The protection circuit is reset by turning the amp off for a few moments and then turning it back on."
Teach me to skim rather than read properly!