50V/0,5A is the VAS power supply, so it will suck few Watts only and can be also only 50V/0,1A, but the secondary winding wire diameter must withstand 4.700 uF capacitor charging current at power-on phase.
Global closed loop voltage gain is related to ratio 2k/100+1, so in your case 21. Open loop voltage gain is another story involving Re, Rc, VAS source impedance, etc.
P.S. Leave 100 ohm GND resistor as it is. If you change the values of the four current feedback resistors you change the fb loop current and therefore you influence the frequency bandwidth too. Please see the CF amplifier references in Wikipedia.
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It is +1
In a case of 1k and 100 ohm feedback resistors the output voltage is exactly eleven times higher than the input voltage, please find it for yourself, it is logical.
Your example: 2k/1k+1=3 (times)
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I was waiting for a chance for ask if SSA input stage suitable for modifying it to a differential input stage without referencing the signal to ground. Maybe this will benefit avoiding a cap at input for blocking possible dc.
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...... PCB without relay , maybe more elegant , and with larger heatsink
I expect QC to do the job , and I will post PCB rev 1.8 in B&W .
Alex.
QC started ... now
Here is a circuit that uses the Rush Cascode :
http://gaedtke.name/SubMenu_Verstaerker/KompDiffAmp-Dateien/KompDiffAmp.pdf
http://gaedtke.name/SubMenu_Verstaerker/KompDiffAmp-Dateien/KompDiffAmp.pdf
...... PCB without relay , maybe more elegant , and with larger heatsink
I expect QC to do the job , and I will post PCB rev 1.8 in B&W .
Alex.
QC report:
- face BJT's in left current source like on the right
- resistor between 4,7V and 15V zeners is 2,2k/2W (two)
- 1uF capacitor between 4,7V and GND is missing (two) – very important GND decoupling (to input GND)
- parallel to 10.000uF put also decoupler cap 1uF/63V – 5mm pin dist
- IRF gate resistors 000 are actually 47ohm degeneration resistors (silk change)
- please put 2 oposite gate protection zeners on each IRF like in SSA Basic, I will put them in sch later
- IRF9610 Source and Drain are mixed, it should be the Source to Base 2SA1987 and Drain to Base 2SC5359
- GND (SPK -) faston in between existing GND connectors is missing
- this SSA is more powerful than SSA Basic, so all the output traces should be thicker
That's the report from QC department.
Alex you are the best, regards Andrej
...... PCB without relay , maybe more elegant , and with larger heatsink
I expect QC to do the job , and I will post PCB rev 1.8 in B&W .
Alex.
Great boards latest ones alex! Especially without the diodes and output relay (although easily jumpered). I'm liking the higher voltage. +-50V is what I've got available to use, and I want to build this version (+-50V BIGBT). But, I don't have the +-60V for the front end.
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