Hello probably being really daft here, but some of my voltage regulators have plastic tabs rather than metal. I’m looking to improve my PSU design by adding heatsinks but I’m confused by the plastic tab. Are they still for heat dissapation?
Do they look like this?:
They’re in a package not designed for high current applications so they don’t have a metal tab. You won’t be able to attach a heatsink without some major fudgery. If you’re planning to power more than a couple of modules with this design I’d suggest switching to a different package for your regulator otherwise you’ll risk letting out the magic smoke.
Tayda sells the L7812/912 regulators for dirt cheap if you need an alternative for conventional half wave rectifier designs but without any more details on your circuit I can’t comment further.
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Details please on these plastic tab regulators? Part number? Source? Photo?
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No, they have the heat tab as I mentioned but it’s plastic not metal. That’s what confused me . I can’t remember whether the one I have is LM7812 or 912 ,all rated for 1A iirc
Apologies for no pic or part number ,was meant to be a generic query
Is the tab simply an isolated tab to protect from shorts?
You see this often on the ‘gainclone’ chips like the lm3875.
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Ah maybe ! I’ll try and find the exact part number and look for the datasheet but that makes sense
Could the tab just be blackened but still metal?!
It’s plastic =, well feels like it anyway
I was looking for a pair of 78/7912 regulators and found a TO220 3V3 regulator with a VERY PLASTIC wing. But maybe it is “termo plastic” … 
Or it is constructed to be able to dissipate the heat accordingly.
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Looks plastic to me haha. Although as long as the bottom side is still metal I imagine it isnt too big of a deal.
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I believe the package type is isowatt220. If you search for 7812cp you’ll find them.
It should be the same as the metal tab kind, only you don’t need the mica insulator when using a heat sink. I have used them in place of metal types and have had no problems yet, make sure to use good heatsink and remember max current goes down as you drop more voltage over the regulator.
You can download a datasheet with the 7812cp here:
https://www.hobbytronics.co.uk/voltage-regulator-l7812
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Thank you I think this is what I have. I was indeed trying to figure out if I could use it with a heatsink this makes sense
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