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Old 15th February 2004, 07:52 PM   #1
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Default Bridge and Parrallel Output Resistors.

When bridging and paralleling four or more chips (OPA541 in this case), resistors are required to connect the outputs of the chips (see image).

I am building an amp using bridging and paralleling, and I hope it to produce 150W+ into 8ohms. On the circuit diagram I am following, 10W resistors are specified.

All of the output power from the chips goes through these resistors, so in theory, I need ~40W resistors, or I will have to limit my output power to 40W.

Has anyone else thought along these lines, or am I being stupid, and I have nothing to worry about?
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Old 15th February 2004, 08:50 PM   #2
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oops, forgot the image.
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File Type: gif resistors.gif (17.5 KB, 155 views)
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Old 15th February 2004, 08:51 PM   #3
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1 How much current will flow through the resistors at full output load?

2 Which value did you have in mind for these resistors? EDIT: 100 mohms.

3 How much power will each resistor develop?

Something to think about.
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Old 15th February 2004, 09:35 PM   #4
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Default Re: Bridge and Parrallel Output Resistors.

Quote:
Originally posted by Matttcattt
When bridging and paralleling four or more chips (OPA541 in this case), resistors are required to connect the outputs of the chips (see image).

I am building an amp using bridging and paralleling, and I hope it to produce 150W+ into 8ohms. On the circuit diagram I am following, 10W resistors are specified.

All of the output power from the chips goes through these resistors, so in theory, I need ~40W resistors, or I will have to limit my output power to 40W.

Has anyone else thought along these lines, or am I being stupid, and I have nothing to worry about?

You'll get a rough idea as a percent of the load power. If your load is 8 ohms and you use 2x0.1ohm/leag res. than your power dissipation is 8/0.1=80 times less than the load, so for 100W/80=1.3W over a 0.1ohm resistor. I think 0.1ohm/2W res will do fine for 100W/8ohm load.
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Old 15th February 2004, 10:35 PM   #5
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Default Re: Re: Bridge and Parrallel Output Resistors.

Quote:
Originally posted by GregGC



You'll get a rough idea as a percent of the load power. If your load is 8 ohms and you use 2x0.1ohm/leag res. than your power dissipation is 8/0.1=80 times less than the load, so for 100W/80=1.3W over a 0.1ohm resistor. I think 0.1ohm/2W res will do fine for 100W/8ohm load.
ok

im just being stupid
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