The LM78XX series of three-terminal positive regulators. fixed output voltage and TO package – are designed for a wide range of applications. Datasheet. DS – Rev 36 – September For further information contact your local STMicroelectronics sales office. LM datasheet, LM circuit, LM data sheet: FAIRCHILD – 3- Terminal 1A Positive Voltage Regulator,alldatasheet, datasheet, Datasheet search site.
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Dedicated to experimental electro-acoustic and electronic music. Live streaming at radio. View unread posts View new posts in the last week Mark the topic unread:: Mar 17, Posts: Fri Aug 11, 8: Troubleshooting big circuit bent project running off LM Having trouble finding existing related topics at the moment, and other electronics forums touch on the subject but are often going over my head.
It is a TO package, currently using this little heat sink: It works, but I measured about mA being drawn from the 6V line, at which the regulator gets too hot to touch very quickly. The bulk of the heat must be coming from the 6V difference from supply? eatasheet
If I understood what I read around at all, I am needing to dissipate around 2W. Can anyone tell me how to calculate?
Jan 14, Posts: Moon Base Audio files: Sat Aug 12, 3: I’ve never done any calculations myself and it’s not that easy as there are a lot of variables. Usually I just put a heatsink on it and if it gets too hot to touch I use a bigger one. A quick search led me to this page which might be helpful and shows how many variables there are.
Something else you might be able to do is reduce the current draw for the 6V section. For example if there is an amplifier in it which is drawing most of the current you might be able to replace that with a 12V one. Feb 27, Posts: San Diego Audio files: Sat Aug 12, I played around with the calculator in PHOBoS’ link with the numbers from the heat sink and LM data sheet and the 2W of dissipation sounds about right.
Came up with a heat sink temp of about 40C which would be pretty warm edit: According to a quick google, too hot would be about 50C to 60C. The problem is that voltage regulators are meant to do just that – regulate. That’s asking a lot. Sun Aug 13, 4: I did try some calculations myself and it depends a lot on the ambient temperature you use.
Without a heatsink it gets easily above C. A DC-DC converter might indeed not be such a bad idea it’s definitely more efficient, although it could cause some unwanted noise. Sun Aug 13, 1: Sun Aug 13, 2: I hadn’t even noticed that and used the 7. One should always consider the maximum possible working temperature of the circuit: The reason is because without a blower the temperature in the neighbourhood of the heat sink is higher than in the rest of the room.
I used 25C since that most likely matches the situation of sitting there testing out your new circuit with the chassis open and putting your finger on it to see if it’s getting hot.
But ya, at some point the different ranges need to be taken into consideration before you pack it in a chassis and expect it to work over a variety of conditions. Apr 17, Posts: Sunny Oakland California Audio files: Thu Sep 14, 9: I don’t want to discourage your exploration with circuit bending, and I’ll say i don’t know how much experience you have with circuitry given your posting here about THIS question and given the very intellectual back and forth you likely know whats up but to any folks still leaning I’d say you were bending in dangerous territory.
Circuit bending can lead to some whackiness and you never know with bending – things can happen and you might get hurt.
LM Datasheet(PDF) – Fairchild Semiconductor
I don’t think it’s been suggested but why a 12v adapter Mon Oct 30, 9: What do you guys think of this? Will the usual cap filters fix that?
I did manage to drop to 9V supply – the higher voltage was originally to suit a Synthrotek Vac-Pak CV circuit, but they work datashert on 9V. The circuit bent part of the project itself only wants 6V. At 9V supply the regulator doesn’t get hot enough to burn you, but still uncomfortably hot with the current heat sink.
I’m sure it’s lifespan will be affected. Wed Nov dtasheet, I have no experience with it so can only guess but I would think it is much more effecient and therefor doesn’t get so warm.
As for noise, if it does turn out to have some unwanted effect you might be better off using an inductor or a combination of an inductor and a capacitor. Dec 09, Posts: Tue Dec 11, Getting right heatsink seems like more dagasheet than building good psu, although i found one has to understand only a few basics to get sufficient heatsink.
I tend to regulate heaters which can be a liittle hard at first because of lots of heat in some cases. After my stock of huge heatsinks, instead of understading how to calculate what’s needed dried up, this article teached me and showed further reading for understanding how to buy buy cheapest one that work well: They can be done with fets instead of bipolars which offer even lower power components. Such circuits work very good for voltages over 40V which can’t be done with ussual regs.
Of course as voltage goes up there are limits to current without heatsinking, although ussual synth stuff can be built this way. I rather don’t get into pentodes like EF86 which are very expensive NOS of course what’s left are mostly rejects or very expensivefortunately both types and many more are still in production sounding the same as NOS, lifetime is a bit shorter Display posts from previous: Please support our site.
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