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These boards are never meant to go into big production. Just a way for Linear to show of there components.

Btw, they not always cost a lot, after showing interest in one to my local Linear rep he just told me one is coming my way free of charge. I love Linear for that.
How much power would be available if a temperature difference of 70C or 80C could be maintained? Thanks.

Like Dave explained so marvellously in his video, stating a mere temperature difference doesn't tell you squat about the power you can expect.
Depending on your system you will have a certain thermal resistance from the medium providing the heat, through the Peltier device, into the medium dissipating the heat. That thermal resistance will determine how much heat (as in watts) will flow through the Peltier device at a given temperature difference. And if we assume an efficiency of 5%, then 5% of that heat flow will be converted into electrical power.

The datasheet shows the temperature difference between the hot junction and the cold as being dependent on the electrical power being input when used in peltier mode, so does the reverse applies in seebek mode?

Perhaps I should rephrase my question:

Under ideal conditions, including a heat source of zero impedance, what is the maximum electrical power that this device can deliver?
and how about under optimal real-world conditions? What would the hot and cold temperatures be?

Thanks for all your replies, im working on the board now and implimenting your suggestions!
I shall post an update when it is done :)
A friend fixes cryostats. But he says he deals with ribbon cables, but not flatflex. If you can use ribbon there is plenty of constantan ones -
Does it have to be flex?  Coax I would think would be more common for cryo / vacuum applications.  Not sure where you go shopping for physics lab toys, but such a supplier would be the first place to check I think.  It's going to be $$$ either way.

I think I'd be pretty surprised if flex can be made in the same way as usual, from metals or alloys other than fairly pure copper.  The ductility and electroplatability of elemental copper is perfectly suited to its use in printing, which is a wonderful coincidence for being the second most conductive metal.  One option would be vaporized or sputtered metal (thin films), which can still be etched like copper circuits, and is suitable for many elements, alloys, and even nonmetallic compounds, but the deposition process is very different and probably expensive, especially if you need a thick layer.

For any connection at all, you might settle for thermocouple wire, which of course is available in various special alloys... typically in matched pairs (though you probably only want just the single strand..).  You might well be better off making your own from wire strips and Kapton tape.

Why is the resistance a problem?  Is it not simply sufficient to put a 1 ohm resistor in series, so that that 0.1 to 0.001 ohm variation from the cable disappears in the same way?  You literally gain nothing by going to the trouble of getting better (or worse, really) alloys.  In the extreme case, a current loop has no regard whatsoever for the resistance, which is why it's been so popular in low-rate signaling for the last.. century and a half or so. :)  Likewise, for the transmission line, if it's normally losing 0.5dB, and it loses 0.05dB when cold... why do you really care at that point?

Anything you can do to arrange the measurement as a ratio, or with Kelvin leads, or a locally matched difference, or so on, will not only improve such problems as tempco and noise, but will only improve the measurement of whatever physical phenomenon you're trying to measure.

General Chat / Re: Need to budget? (Money stuff)
« Last post by TerraHertz on Today at 03:51:56 PM »
Another advantage of pen and paper, is it leaves permanent records on file. Without the further expense of a printer and printer consumables, or any worries about digital media failure.

Also one simple habit - writing the date at the top right of every blank sheet of paper you're about to use, to write anything at all - makes a world of difference. How I wish someone had bashed that obvious truth into my head back in my teens/20s.
This is for cryogenic use.  Copper has too high a thermal conductivity, which is directly related to electrical conductivity.  What is worse, copper changes resistance (electrical and thermal) by a huge and unpredictable factor at low temperature due the exact quantity and type of impurities, as well as work hardening or annealing..  Pretty much any sort of alloy will work -- the tempco doesn't have to be exactly zero -- I just need a nice resistance of about 0.5 - 1 ohm that doesn't have huge changes with temperature.  Eventually I would like to use this for high frequency as well (a few GHz), so a controlled impedance would be nice (I don't mind a loss), but at the moment this is strictly low frequency (kHz).

I can't think of any other reason someone would want this, so it isn't surprising it doesn't exist off the shelf.  I just thought I would ask because you never know what some aerospace or medical application might have created that I could piggy back off of.

I've got some DIY ideas, but probably if it comes down to that I will probably just look for a custom cable assembly place and keep using the wiring we are using now.
General Chat / Re: How Good is the EEVBlog?
« Last post by ivaylo on Today at 03:48:20 PM »
The Searcher will not bother us again.

Much better than locking this thread.
Agree, although it feels tainted now...
I know that upthread Corporate666 complained about buyers who are quick to open credit-card disputes, but if the customer is honest and the seller is a crook, the FIRST thing the customer should do is open the dispute with the credit issuer, and then he should open the dispute with eBay and PayPal.

Only if you don't care if PayPal closes your account  :(
I have been the victim of a vendor who ran out the clock for eBay/Paypal restitution.
(I know better now).
But I got ALL my money back because I instituted a chargeback via my C/C (much longer time limits).

Paypal did nothing to my account. (They have in the past frequently asked for me to associate my paypal account with something other than a credit card - I wonder why? - but their automated emails have dried up).
You are right!, I actually never noticed that. This means that I was numbering pins incorrectly and side with pins 1-8 must be grounded because control pins are on the other side.
I replaced sensor board with a pot and device behaves exactly the same (measurements go into overload in a few different places on the pot scale, its only possible to get temperatures of -50 to about +30 on the scale, then it sits on +955 on the upper third of the potentiometer movement range). I am now convinced that the termophile itself is ok. I wonder if this can be calibration data issue. But unless there is a full table mapping all possible ADC inputs to measured temperature in that EEPROM I don't think it should behave that randomly.

Knowing the correct pin numbering I identified pins of HCF4053 12,13 as inputs and pin 14 as output. But then I discovered that this analog mux is not simply feeding measured IR signal and thermistor reading separately into ADC but rather doing some sort of range switching. On the closeup photo a trace can be seen that connects thermistor pin from sensor board straight into first input of the MUX. But this signal is also on the other side of the board routed into that analog network. And in fact this is the signal that is supposed to be on the output most of the time (which I discovered by probing "A" control pin). Only when I simulate (via pot) input signal at quite high level control signal A becomes high (selecting second input) with short low pulses once a second or so (maybe the program is checking if it should "range down" again).

Now, about checking that HCF4053.
I must admit that I never worked with such device and I am a bit puzzled about how it exactly works. I cannot measure channel resistance in circuit but when the input is selected it seems to sit on the same level as the output.
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