Hi all, could you please tell me the reason why the resistance in a CRC supply is usually made by putting resistors in parallel and not just using one resistor. The Pass type of supply seems to use 4 x 0.47 ohm. Could this be substituted for a 0.1ohm of a higher wattage, or are there other reasons why parallel resistors are better.
Thanks for your help
Alan
Thanks for your help
Alan
Yes, you can use a single resistor of higher, it's just a matter of watts. The
parallel resistors are just handy and usually cheaper.
😎
parallel resistors are just handy and usually cheaper.
😎
Thanks for your replies, much appreciated. Forgive me for being so stupid, I have been doing some calculations regarding the wattage of the resistor and I have as follows:
1.5 amp current draw ( bias current ) through a 0.1 ohm resistor gives a volts drop of 0.15V and a power dissipation of 0.225W Where have I gone wrong please?
Alan
1.5 amp current draw ( bias current ) through a 0.1 ohm resistor gives a volts drop of 0.15V and a power dissipation of 0.225W Where have I gone wrong please?
Alan
and if this is a push-pull amp driving 2ohm you have a peak current of 12A. Thats a voltage drop of 1.2V, wich means 14.4W. And then there is charging of the caps.
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Follow on from this, can you use an umbilical lead as the resistance in the CRC? I plan to build a power supply in a separate enclosure to power my growing stable of FW clones and I'm thinking that a lead of about a meter or so from the power supply to the amp. I will have capacitor banks in both enclosures.
yup
Just watch the AVERAGE current, because that is where the main heating (softened insulation) of the umbilical will come from. P=I²R
Just watch the AVERAGE current, because that is where the main heating (softened insulation) of the umbilical will come from. P=I²R
pass aleph 30 power supply
Could i ask some noob questions about this topic? I'm building power supplies for mono aleph 30's using pcb's with the following lay-out: 4x 22000uf 6 resistors 4x 22000uf 2x 4.7uf. Is this enough storage? I have never build a class A amp. (Only some modified quad 405's)
If i did my homework correctly i need 0.1r for resistor value in a crc power supply? So 3 x 0.33R in plus and minus?
The transformers i'm using for each amplifier are 18Vac 625VA putting out a total of 34.8A with parallel windings.
Would this be more then enough because it's mono. (Or way to much, 34.8A, for one channel?)
The big question is, how much wattage do i need for the resistors? And if i put resistors parallel does the wattage double?
BR
Could i ask some noob questions about this topic? I'm building power supplies for mono aleph 30's using pcb's with the following lay-out: 4x 22000uf 6 resistors 4x 22000uf 2x 4.7uf. Is this enough storage? I have never build a class A amp. (Only some modified quad 405's)
If i did my homework correctly i need 0.1r for resistor value in a crc power supply? So 3 x 0.33R in plus and minus?
The transformers i'm using for each amplifier are 18Vac 625VA putting out a total of 34.8A with parallel windings.
Would this be more then enough because it's mono. (Or way to much, 34.8A, for one channel?)
The big question is, how much wattage do i need for the resistors? And if i put resistors parallel does the wattage double?
BR
good enough ...
resistors - power is added , be it parallel or series connection
web is full with basic tutorials
Basic Car Audio Electronics
resistors - power is added , be it parallel or series connection
web is full with basic tutorials
Basic Car Audio Electronics
Guess i have to do some reading......
On the website you posted it says : "One watt of power is dissipated in the form of heat when one*amp*of*current*is forced through a one ohm*resistor."
Does this apply here?
34.8A of the transformer x 0.1ohm, thus a resistor of 3.48w will do? (Or do i need to calculate every resistor seperately . The 3x 0.33r)
Other words,is it as simple this?
On the website you posted it says : "One watt of power is dissipated in the form of heat when one*amp*of*current*is forced through a one ohm*resistor."
Does this apply here?
34.8A of the transformer x 0.1ohm, thus a resistor of 3.48w will do? (Or do i need to calculate every resistor seperately . The 3x 0.33r)
Other words,is it as simple this?
for current you need to take quiescent one (Iq) , not hypothetical short-circuit-bigbadaboom one
btw. P=I^2 x R
if Iq is 2A , that means dissipation on 0R1 will be 400mW , so having 3 pieces of 3W in parallel will give 9W .......... plenty of reserve in my book , even for powering up peak currents (read - fillin' da caps)
btw. P=I^2 x R
if Iq is 2A , that means dissipation on 0R1 will be 400mW , so having 3 pieces of 3W in parallel will give 9W .......... plenty of reserve in my book , even for powering up peak currents (read - fillin' da caps)
Last two questions if i may Zen Mod,
I see most people use metal oxide resistors on the psu and amp pcb's ( panasonic erg3sj if i'm correct? ). Are these the best i can use for the application?
The quiescent you talked about, does the same apply if i should use inductors instead of resistors? Around 2.2mH, Low as possible dcr and capable of 12a continuous current?
I see most people use metal oxide resistors on the psu and amp pcb's ( panasonic erg3sj if i'm correct? ). Are these the best i can use for the application?
The quiescent you talked about, does the same apply if i should use inductors instead of resistors? Around 2.2mH, Low as possible dcr and capable of 12a continuous current?
resistors - MOX are best bang fro the buck (eurocents in your case) , but you can use also classic wirewound ( white rectangular ones) or MPC (skinny white rectangular ones)
chokes - yes , you got it what's important
either big chunky air cored or big chunky iron cored
please , no tiny common mode ferrite cored chokes,intended for RF ; it's sorta fashion lately around , to ask for these
chokes - yes , you got it what's important
either big chunky air cored or big chunky iron cored
please , no tiny common mode ferrite cored chokes,intended for RF ; it's sorta fashion lately around , to ask for these
Was thinking something like a jantzen audio 2.2mH 14awg c-coil. Jantzen states it is very suitable as a psu inductor. Has a dcr of 0.06 and max 700w continuous for 48hrs. Not bad at all i think. Use them a lot in crossovers. (Bass)
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