EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Chris56000 on August 26, 2022, 03:49:24 pm
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Hi!
Does anybody know where I can obtain 10 off 4R02 ±1% 2W 2512 chip resistors, equivalent to Stackpole Electronics RMCP2512FT4R02 or an equivalent?
It's to build the Front Board of Paul Vee's Curve Tracer Mk. 3 described in "Paul's Electronic DIY Blog".
Chris Williams
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You have a couple of options at second-tier distributors: https://octopart.com/search?q=2512+2w+4.02ohm¤cy=USD&specs=0&in_stock_only=1 (https://octopart.com/search?q=2512+2w+4.02ohm¤cy=USD&specs=0&in_stock_only=1)
You can buy these and overdrive them: https://www.mouser.com/ProductDetail/71-CRCW25124R02FKEGH (https://www.mouser.com/ProductDetail/71-CRCW25124R02FKEGH) , knowing that getting 2W out of a 2512 in the first place is something of a dicey proposition, so what's another half watt between thermal enemies?
Or you might call up Venkel and try to buy a small reel.
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OP, just to point out this resistor is part of the magical unicorn series that many resistor manufacturers offer. Stackpole and Yageo.
2W in a usual 1W package, for a given resistor size the only way to obtain a higher power rating is using materials good for higher temperatures - which means it runs super hot.
"The thermal resistance of the RMCP will be similar to the RMCF. For example, the RMCF2512 and the RMCP2512 will have similar surface temperatures at 1W; the RMCP is designed to withstand higher temperatures associated with high power levels."
Graph: at 1W it's 150°C surface temp. RISE? for the 2512 size so lets cook the unicorn at 2W. It's just unrealistic but sorting by that parameter when buying parts and seeing "2W" people will believe it's true.
Yageo (https://www.yageo.com/upload/media/product/productsearch/datasheet/rchip/PYu-RC_Group_51_RoHS_L_11.pdf) also offers a "2W" 2512 i.e. RC2512FK-7W4R02L
Neither datasheets mention the actual 2512 temperatures at 2W, it's just a marketing fantasy.
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I like the name Flobbydust. I have one of the original Flobbydust books around my lab somewhere. Yes the 2W rating is a joke. I did find that the 2 or even 3 W rated 2512's have larger solder pads. That is why we chose them. Not that we think they can actually dissipate that much power. However they can dissipate more than the smaller pad sized 1W resistors. We also relied on more footprint dissipation on the PCB. The power that needs to be dissipated by these resistors is not 2W. It varies by duty cycle and current maximum settings.