borislavgajic wrote:is it possible to connect two different tubes....ecc83 and ef86....on 12,6V heater voltage?
and how...if that can be done.....?
thanks
boris
frequencycentral wrote:I think I got the math right!
frequencycentral wrote:Therefore run the two in series from 12.6v
lolbou wrote:frequencycentral wrote:I think I got the math right!
+1 Rick!
Calculations checked OK. Please accept this A+ grade from an humble physics teacher!
briggs wrote:Ahhh, very nice solutions! I apologize for my earlier BULLSHITE answer when I hadn't bothered to check datasheets. I hope it caused no distress!
Ok - now here is another question for the heater calculators! I'm going to need to run a 6112 submini a 7327 submini and an ECC99 off of either 18.9V or 12.6V, how do you lot think it would be best to do this
briggs wrote:Having thought about it again - here is the situation I find myself in (see the attached picture). Now I need to power this setup from the 15Vdc supply I have. Confusion ensues especially after a few beers on a friday eve! Legitimate values for R1 & R2 are required!
frequencycentral wrote:briggs wrote:Having thought about it again - here is the situation I find myself in (see the attached picture). Now I need to power this setup from the 15Vdc supply I have. Confusion ensues especially after a few beers on a friday eve! Legitimate values for R1 & R2 are required!
Why not just use a 7812 to regulate the 15v down to 12v and dispense with the resistors?
briggs wrote:EDIT - When I calculated it like that Rick I got 18 ohms, I must have done something wrong>! What method did you use? I could do with some practice!
frequencycentral wrote:briggs wrote:EDIT - When I calculated it like that Rick I got 18 ohms, I must have done something wrong>! What method did you use? I could do with some practice!
DC voltage = 15 volts
Tube heater's (combined) power requirement = 12.6 volts @ 700ma
Voltage drop required = 2.4v (15 - 12.6 = 2.4)
2.4 (volts) x 7 (hundred ma) = 16.8 (ohms)
2.4 (volts) / 0.7 (amps) = 3.4285 (watts)
Therefore 16.8 ohm 3.4285 watts. In reality a difficult value to find, so go for the nearest 'easy' value, 18 ohm 5 watt. Always better to have the wattage over-spec'd.
If Loubou agrees, I might get another A+......!!
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