Regulator problems

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kinski
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Post by kinski »

So I’m having a weird issue. I’ve used regulators countless times over the year to drop voltages to where I need them to be.

For a few years I’ve been using an 18v regulator with a 24v 4A power supply. Works beautifully. However, if I try to add a 9v regulator, the regulator over heats or goes up in smoke while the 18v regulator continues to remain stable and cool. Any ideas what could be happening here?

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karul
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Post by karul »

bigger the difference between input and output voltage, bigger the heat. 24-18=6V, 24-9=15V avoid using big differences between input and output voltage. do you use heatsinks? how much current you need to draw from 7809? take a good look at the datasheet.

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Post by Manfred »

Edit: Sorry Karul, you wrote the same facts just before me while I was still writing my post.
kinski wrote: 07 Aug 2022, 18:57 So I’m having a weird issue. I’ve used regulators countless times over the year to drop voltages to where I need them to be.

For a few years I’ve been using an 18v regulator with a 24v 4A power supply. Works beautifully. However, if I try to add a 9v regulator, the regulator over heats or goes up in smoke while the 18v regulator continues to remain stable and cool. Any ideas what could be happening here?
The differential voltage between output and input is 24 volts - 9 volts = 15V.
The power dissipation at the voltage regulator is calculated as 15 volts x load current.
I would say that the maximum power dissipation is exceeded in this case, the voltage regulator needs a suitable heat sink.
What type of voltage regulator is it, what is the load current.

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kinski
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Post by kinski »

Ah! Ok, I thought I was within spec for this. I had the regulator screwed against the enclosure. Figured that would be act fine as a heat sink and act as a ground. Could I power the 9v regulator with the 18v regulator?” That’s in the same enclosure?
Probably don’t need more than a couple hundred ma tops.

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karul
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Post by karul »

kinski wrote: 09 Aug 2022, 20:01Could I power the 9v regulator with the 18v regulator
yes, here is an example from Soundcraft Spirit Powerstation power supply, powered mixer designed by Douglas Self
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psu.webp

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