Power Supply Question: Can It Handle 6A @ 35V?

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Discussion Overview

The discussion revolves around the capabilities of a power supply to handle a load that draws 6A at 35V, and the implications of using a resistor to limit current. Additionally, there is a related inquiry about the behavior of amplifiers in bridge mode and their power delivery to speakers.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether a power supply rated for 4A at 35V can power a device that requires 6A, suggesting the use of a resistor to limit current.
  • Another participant explains that using a resistor will create a voltage divider, resulting in insufficient voltage across the device, which may prevent it from functioning properly.
  • A different participant asserts that if the device needs 6A, it is unlikely to operate correctly with only 4A, and adding a resistor would worsen the situation, recommending a more powerful power supply instead.
  • A later post shifts focus to amplifiers, asking whether using two amplifiers in bridge mode with 8-ohm speakers would effectively double the power delivered to each speaker.
  • Another participant responds that while bridging amplifiers can theoretically deliver double the current, the actual power output depends on the amplifiers' ability to provide sufficient current without clipping.

Areas of Agreement / Disagreement

Participants generally agree that a power supply rated for 4A is inadequate for a device requiring 6A. There is also consensus on the limitations of using a resistor in this context. However, the discussion about amplifiers in bridge mode introduces some complexity, with varying interpretations of power delivery and current handling.

Contextual Notes

The discussion includes assumptions about the behavior of power supplies and amplifiers that may depend on specific conditions, such as the characteristics of the devices involved and the power supply's specifications. The implications of using resistors and the concept of bridging amplifiers are not fully resolved, leaving room for further exploration.

Who May Find This Useful

Individuals interested in power supply capabilities, circuit design, and audio amplifier configurations may find this discussion relevant.

Tesladude
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Ok this may be a stupid question but what the heck.

If I have a power supply giving max of 4amps with 35v
and what I am powering draws 6 amps at 35v,
then that means the device has 5.7 ohms of resistance.
If I put a 3.05 ohm resistor (ish) then this will drop the amps down to 4, but will it still power the device... functionally?
 
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The resistor and your device will form a voltage devider. You'll get 5.7/(5.7+3.05) * 35 = 22.8 V across your device so it is not likely to work.

The power dissipated in the resistor is I^2 R = 4*4 * 3.05 = 48.8 W which will be a problem as well.
Your resistor might require a heatsink and a fan.
 
if the device needs 6A to operate then its not likely to work with only 4 amps or if it does it will be unstable in operation
Adding a resistor is only going to make the situation worse

you need a beefier PSU

Dave
 
ok thanks, I forgot about the voltage divider so It seemed possible for a moment, this isn't a project I'm working on, I was just day dreaming.

BUT

Sense I have this thread open, and davenn is here:

I read that bridge mode in amplifiers will, for example, take a 100 watt amplifier at 8ohms and turn it to a 200 watt amplifier at 4ohms.

I was going to use 4 tda2050 amps, each running one speaker, but if I use 2 amps in bridge running 2 8ohm speakers in parallel, would this give me double power into both speakers? So as if each speaker had it's own amplifier twice as strong?
 
As long as you realize that you don't get anything for nothing then you can't go too far wrong. Connected in a bridge, two amplifiers will (if they can) deliver twice the current into a load than they would, individually. They are each 'seeing' a load of half the resistance of the original load. If the amplifier can't deliver enough current then you won't get that power - it will clip.
 
ok thank you! I must say you explained that very well, someone else I asked wasn't being too clear haha.
 

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