Measurements with R1 17R:
DCin 15.35-15.40V
Across dummy load 4.71V
Across R1 4.92V (0.289A, great)
Across R2 6.35-6.39V
Across LEDs 9.07V
DCin 15.35-15.40V
Across dummy load 4.71V
Across R1 4.92V (0.289A, great)
Across R2 6.35-6.39V
Across LEDs 9.07V
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Time to remove the dummy and feed a heater I guess. Keep the DMM there from the very start to see it develops about the right voltage across the filament and steadily so. If you see over bright or moving voltage a lot, stop.
CCS heating is slow start VS voltage heating, so don't be surprised if it will take a minute or two to top.
It doesn't make sense. The voltage across the tube should be in the 6V range. Obviously the current drawn is not bad. Maybe you have a bad tube, or bad connection to the filament.
Sorry Iko, the 6922 is mounted in SRPP (shunt regulated push pull) with 2 tubes x channel so I disconnected one tube & yes now the voltage across the tube connected is 5.98V
How can do for 2 tubes? increasing the current till 0.6A changing R1 value?
How can do to get 6.1V?
How can do for 2 tubes? increasing the current till 0.6A changing R1 value?
How can do to get 6.1V?
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If the the two tubes have their filaments connected in parallel, then certainly the current drawn is different. If you had four tube filaments in parallel, expect 300mA x 4 to be drawn. Make sure you got all of this right. How many tubes are connected in parallel, so that the CCS is feeding them?
The schematic is quite small. But it seems to me that you have four filaments in parallel. Therefore you will have four times the current draw. You have to change R1 to be smaller to allow 4x300ma=1.2A. Are you sure R1 will take it? Are you sure the mosfet has enough heatsink?
I think it's a bad calculation !
You can't have only one CCS for 4 Filaments,
if you forget to plug 3 tubes, and only one is driven by CCS 1.2a >>>> PLOUF.... Blackened......Dead
You MUST have a CCS per tube (but it's a bit too much, to my taste)
R.C.
Ciu is right; one current limit to four parallel filaments is a bad idea. If one of the filaments will draw more than the others, there is nothing to stop it.
As complement...
For me, a CCS is not a good solution, because you can't exchange any tube with another, because each one is specific in heating current, may be a bit, but real difference
I've just had this problem with 6n23p-ev, a month ago, when I wanted to wire in series with a 12.6 source
I prefer to use LM317, in "slow turn-on voltage regulator"...
R.C.
For me, a CCS is not a good solution, because you can't exchange any tube with another, because each one is specific in heating current, may be a bit, but real difference
I've just had this problem with 6n23p-ev, a month ago, when I wanted to wire in series with a 12.6 source
I prefer to use LM317, in "slow turn-on voltage regulator"...
R.C.
For heating multiple 6.3V heaters in parallel, just use the original Audio Note schematic shown above. The bottom section, with the 7V5 zener, and emitter follower.
I agree, use current sources only for 1 heater, unless you have series-string valves, like PCC88 etc.
I agree, use current sources only for 1 heater, unless you have series-string valves, like PCC88 etc.
Hey guys, now I'm in middle of the dance & I can't stop, it's enough one CCS 0.3A per tube or have to be 0.6A per tube?
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