Hi Tim One last option that's possibly even better, but requires rudimentary electronics: if you find the logic gate that flips from 0 to 1 (or backwards) upon thermocouple triggering below threshold temperature, you can simply supply +5V to the appropriate spot on the PCB, and Bob's your uncle.
To find the spot one has to trace the connection a bit, and have a handy voltmeter with a circuit probe, so when you put the TC into cold, it will register the signal. This assumes a fairly simple operation of the circuit - it may be that something much more sophisticated is taking place, like a signal on a CAN bus or god knows what else. All the best, Artem - Cosmic Cats approve of this message On Fri, Feb 3, 2023 at 2:16 AM Tim Gruene <tim.gru...@univie.ac.at> wrote: > Hi Artem, > > the simulator is exactly what I was looking for - many thanks! > We did build a small circuit to generate the voltage (-0.586mV for > -15C), but this didn't work - probably, our circuit was too simple. 12V > input looks energetically better to me than using a peltier chiller (I > meant peliter, not piezo originally...) > > Second to that I like Mark's idea of a long cable for the couple and > stick it in the next -20C cooler. > > And yes - I already confirmed with cooling by liquid nitrogen, that the > concept works: when the thermocouple indicates cold enough, I can > operate the diffractometer, and hence install our new alien detector. I > was indeed looking for a long-term solution to make overnight > measurements. > > Thanks to everyone. I feel overwhelmed with the large number of quick > responses. > > Best, > Tim > > On Thu, 2 Feb 2023 20:19:32 -0500 > Artem Evdokimov <artem.evdoki...@gmail.com> wrote: > > > A basic Peltier element will likely work (may need a stack of two to > > reach -20) however the simpler option indeed would be to 'fake out' > > thermocouple input using a voltage, as described by Ivan. > > > > https://us.flukecal.com/Thermocouple-Temperature-Calculator > > > > And for $38 one can apparently purchase a thermocouple simulator > > > > > https://www.brightwinelectronics.com/product/temperature-calibrator-k-n-thermocouple-generator-simulator > > > > Artem > > > > On Thu, Feb 2, 2023, 3:42 PM Rajkovic, Ivan < > > 000095c2dc0d4fa4-dmarc-requ...@jiscmail.ac.uk> wrote: > > > > > Hi Tim, > > > > > > Not sure if this would work, but can you get a voltage supply and > > > connect it instead of the thermocouple? You would need something to > > > provide a few mV: > > > https://www.thermocoupleinfo.com/type-k-thermocouple.htm > > > > > > > > > Ivan > > > > > > > > > > -----Original Message----- > > > > From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> On Behalf Of Tim > > > > Gruene > > > > Sent: Thursday, February 02, 2023 11:57 AM > > > > To: CCP4BB@JISCMAIL.AC.UK > > > > Subject: [ccp4bb] small scale -15C chiller > > > > > > > > Good day, > > > > > > > > I would like to cool a K-type thermocouple down to -15C. The > > > > temperature > > > does > > > > not need to be very accurate, nor exactly -15C, just below that > > > > level. > > > > > > > > I was thinking of using a piezo-chiller, but they don't seem to > > > > be very > > > energy > > > > efficient. > > > > > > > > Could anyone make a recommendation for a simple device to cool > > > > the tiny thermocouple to -15C to -20C? > > > > > > > > For the details: we have an inhouse diffractometer with a dead > > > > detector. > > > The > > > > system is blocked, because the temperature of the detector needs > > > > to be > > > below - > > > > 15C. It is measured with a K-type thermocouple. I tested with > > > > liquid > > > nitrogen. > > > > The system show -64C (probably the limit of the thermocoupe) and > > > > I can > > > operate > > > > the system (and mount our new (brand-alien) detector). > > > > > > > > Thanks a lot! > > > > > > > > Best, > > > > Tim > > > > > > > > -- > > > > -- > > > > Tim Gruene > > > > Head of the Centre for X-ray Structure Analysis Faculty of > > > > Chemistry > > > University > > > > of Vienna > > > > > > > > Phone: +43-1-4277-70202 > > > > > > > > GPG Key ID = A46BEE1A > > > > > > > > ################################################################# > > > > ####### > > > > > > > > To unsubscribe from the CCP4BB list, click the following link: > > > > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > > > > > > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, > > > > a > > > mailing > > > > list hosted by www.jiscmail.ac.uk, terms & conditions are > > > > available at https://www.jiscmail.ac.uk/policyandsecurity/ > > > > > > > ######################################################################## > > > > > > To unsubscribe from the CCP4BB list, click the following link: > > > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > > > > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > > > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > > > available at https://www.jiscmail.ac.uk/policyandsecurity/ > > > > > > > ######################################################################## > > > > To unsubscribe from the CCP4BB list, click the following link: > > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > > available at https://www.jiscmail.ac.uk/policyandsecurity/ > > > > -- > -- > Tim Gruene > Head of the Centre for X-ray Structure Analysis > Faculty of Chemistry > University of Vienna > > Phone: +43-1-4277-70202 > > GPG Key ID = A46BEE1A > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
