Which, it seems, you said in order to try to negate their goodness by
not quantifying their weirdness and driftiness, but by merely
relegating them to your scrap heap with the slap of your hand.
Current Controlled Resistor
Jun 09, 2011
37 Replies
Yeah, sure.
Everybody knows that, but what I think Phil was alluding to was the Z
transform from primary to secondary with respect to the turns ratio
and the R in the primary.
On a sunny day (Sat, 11 Jun 2011 17:57:40 -0700) it happened John Larkin wrote in :
Maybe you could combine LDRs with relais and real resistors, and have the LDRs only conduct for a very short time during the relais opening and before an other one closing. That could also solve a power problem, LDRs only dissipating for milli seconds.
Don't know. You'd have to ask him.
Sample? If I'm simulating an RTD into a FADEC, I can't know when it will sample; I can;t know if it samples at all. My job is to behave like a real RTD.
Simulating resistors is an interesting item for discussion, as long as people don't instantly turn it into a battle of insecure egos.
I said that photoresistors are weird an drifty. I didn't say it was your fault.
John
Then, since the slope of a real RTD's resistance change is
infinitesimal, your job is untenable since your attempt at quantizing
it can only approximate its behavior.
An RTD changes almost 4000 PPM per degree C, so 16 bits of resolution, with smooth steps, is plenty good enough. Millisecond shots of resistance excursion isn't. We're not talking philosophy here, we're talking numbers.
I like to talk about electronics. You like to cluck and my-o-my about personalities.
John
swing,
What you're talking is bullshit, not only because all RTDs don't have
a slope of 4000 ppm/K, but because millisecond shots of delta R may
well be plenty good enough if the programmed rate of change of
resistance of your device follows that of the real sensor.
I'm pretty sure I got it but, since you say you didn't, then I think
it's up to _you_ to ask for clarification.
swing,
Irevelant. The problem scales for any type of RTD. It just so happens that most RTDs have TCs around 4000 PPM/K. RTDs are almost always platinum, with the occasional oddball nickel or copper.
but because millisecond shots of delta R may
What I'm talking about is testing jet engine control computers... in real life. If a FADEC trips at some temperature, we need to test it by creeping up the simulated RTD temp until it trips. If we use relays and resistors to simulate an RTD, the step transitions will spike the apparent temperature up and down, which will cause false overtemp trips.
Error? Here? Please be specific.
Silly old hen.
John
Ask a concrete question and I'll try to answer it. So far all I hear is the usual confused clucking.
John
Please...
Why would you want to change the original "relay" to "relai"?
"relais" is a common spelling of "relays" in europe and elsewhere.
John
I concur, I have to deal with foreign prints quite often...
Jamie
Oh, apologies for exceeding the range of your thriving imagination.
Here it is:
/ switch / IN1--------o o-------+ | | resistor | | IN2--------------------+
John
Apologies accepted, but where's the input cap you alluded to?
Well, I suppose that would go - wait, wait, don't tell me - across the input.
John
Instead of just trying to create confusion, which seems to be
your bent, why don't you just place the capacitor where you think it
needs to be located in the schematic you've already posted?
^^^^^^^^^^^^^^^^^^^^^^^^^
Well, some people are, apparently, very easily confused. So much for "thriving imaginations."
John
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