- posted
6 years ago
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
Maybe Martin Shkreli is in charge over at Teledyne.
Cheers
I may as well make my own SSR from a PV coupler and a couple of self-protecting mosfets. More board area but 1/20 the price.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
huh,
GH
Den tirsdag den 27. juni 2017 kl. 22.31.12 UTC+2 skrev John Larkin:
at one point we needed an SSR fast enough (~1ms) to short circuit protect a board full of triacs and capable of ~10A, the only one we found was a big potted block and afair several 100 dollars
in the end two back to back fets and an isolated gate driver did the job
It's self-protecting, but so are the cheap Ixys parts. I wish people would make higher-current self-protecting SSRs; we'll probably make our own.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
So why aren't there more fast, protected SSRs around? They could be SIPs or something, like the cheap dc/dc converters.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
I prefer relays, nice isolation... and they have 'infinite' gain >:-} ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et |
Only latching relays have infinite power gain.
Who makes self-protecting electromechanical relays?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
You could probably get a bit current out of it if you cool it with this $20 fan:
Just the right size.
--sp
-- Best regards, Spehro Pefhany
2 AMPS in a 6-pin DIP? That's QUITE good, they need a really low on- resistance FET for that!
I use a part the same size to make logic level SSRs, and they are good to 50 mA, tops!
Jon
0.121 CFM might blow the part clean off the board.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Here's an 8 amp SOT23
-- John Larkin Highland Technology, Inc lunatic fringe electronics
This one
switching DC.
I wonder if a 2.5A polyfuse would protect it well enough.
--sp
-- Best regards, Spehro Pefhany
We were thinking of a couple of something like this
back-to-back. Then we'd need an isolated gate driver. I think all that protection junk is powered by the gate drive, so the usual PV opto gate driver wouldn't be able to drive the pair. These things need a lot of gate current, like 400 uA.
Maybe a cheap DRQ74 type 1:1 transformer with high frequency drive, and a rectifier on the mosfet gate side?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Hard to believe they want 80 bucks for a protected FET (like the NCV8402) with a built-in photo isolator.
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That's out of their military systems/aerospace division. Everything they ma ke is top dollar. The products are usually high reliability and have extend ed environmental operational range. There was some scandal in the 80s with them cheating the government on the testing.
The military-industrial complex cheating the governmental-military complex?
Oh...my...God...
Should work well. There's no reverse current protection though.
--sp
-- Best regards, Spehro Pefhany
Thereby providing yet another illustration that "private enterprise => good" and "government socialism => bad".
Or not, depending on the colour of your spectacles.
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