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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 6th Mar 2018, 4:20 pm   #1
ITAM805
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Default Regulator query

hi all, is this L78505 just a '7805' by another name?

many thanks
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Old 6th Mar 2018, 4:23 pm   #2
mhennessy
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Default Re: Regulator query

The "S" in the middle means that it's the 2 amp version of the regular 7805.
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Old 6th Mar 2018, 4:26 pm   #3
ITAM805
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Default Re: Regulator query

Ah thanks Mark! Specsavers?
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Old 6th Mar 2018, 5:47 pm   #4
bikerhifinut
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Default Re: Regulator query

Hope ITAM doesn't mind me coming in on top of this.
I've got some 5amp 3 pin regulators of the LD1085 sort (Might be 1086 but without digging em out I cant remember). Now I will be using them in the next few days for a regulator supplying around 3.5A. So the regs are well inside their rating and on a chunky alloy heatsink.
I have to hand a pair of the Velleman 1A regulated PSU boards which is based on a 317 reg and nicely adjustable. I was wondering if I could repurpose the boards by subbing the 317 reg for the higher rated one as the boards would be a nice neat way to do it although I can easily enough hardwire the job on a tagstrip, but as i have these boards anyway and they need to come out of the amp in question It seemed a possible use? You may take it for granted that I will be removing the original 1N4007 bridge as they will be fed with raw 9VAC and also I have a good stock of meaty 10000 uF electrolytics, designed for PSU use for the reservoir caps so the existing puny cap will also be redundant.
If theres any reason I shouldnt then its only a slight amount of extra work to hardwire the reg and I Have plenty of space to do it.
The boards will always come in handy for other projects. I only wish I was skilful enough to knock up a few boards to take a 3 legged reg and ancillary parts but I usually flunk out and use a bit of veroboard!
A.
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Old 6th Mar 2018, 6:02 pm   #5
G6Tanuki
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Default Re: Regulator query

My worry would be that the PCB traces on the 1A Vellemann LM317 reg board might not be up to handling the 3.5A you propose.
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Old 6th Mar 2018, 7:19 pm   #6
bikerhifinut
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Default Re: Regulator query

Quote:
Originally Posted by G6Tanuki View Post
My worry would be that the PCB traces on the 1A Vellemann LM317 reg board might not be up to handling the 3.5A you propose.
That was My main concern too.
On reflection it's probably just as easy to solder the reg up on a piece of chunky tagstrip and use flying leads from the reg(s) to the tags. And in any case its probably better to use fixed resistors in the adjustment leg of the circuit to avoid issues with trimpots? Doesn't have to be 6.3V on the nail a tenth of a volt either way isnt going to be noticeable in performance terms.
A.
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Old 6th Mar 2018, 7:52 pm   #7
Orakle42
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Default Re: Regulator query

The 7800 series have 2 common variants, an"M" after the 78 denotes 0.5amp device and the "S" denotes 2amp devices. The next 2 numbers denote nominal voltage.
EG 78S09 would be 9v @ 2amps, 78M08 would be 8v @ 0.5amps. No eltter is the standard 1amp nomenclature.
A 79 prefix indicates a negative voltage regulator.

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Old 6th Mar 2018, 10:24 pm   #8
kalee20
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Default Re: Regulator query

Quote:
Originally Posted by Orakle42 View Post
The 7800 series have 2 common variants, an"M" after the 78 denotes 0.5amp device and the "S" denotes 2amp devices.
In fact there's also the "L" version, 100mA in TO92 package - plus surface mount variants that I'm not familiar with!
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