Hi Joachim, On 05.06.12 09:08, Joachim Franek wrote: > • 3x temperatur measurement, 12bit resolution (2x nozzle, 1x feader housing)
Is the high resolution needed because the PID temperature controller needs something like ten times the resolution the control loop is intended to achieve, much like a machine axis? (Giving something like 9 bits, or +-0.6 °C at 300 °C, IIUC.) ... > For cheap temperature measurement with 1n4148 up to 400 °C see Bild2 from: > http://thomaspfeifer.net/laminator_temperatur_regelung.htm Well, for a quite limited time. Yes, the predictable 2 mv/°C temperature coefficient of a silicon diode's forward drop is a useful sensor for temperature measurement. If 10 mv/°C is desired, then we can wire 5 of them in series, in lieu of adding an op-amp. But they're typically only rated to 175 °C Absolute Maximum, and suffer shortened life even at that temperature. The Arrhenius equation predicts the accelerated ageing which is observed, and it amounts to a halving of lifetime for each 10 °C rise in temperature. Already at 175 °C, the diode will last 1/32768 (.00003) of the life at 25 °C. I'm curious to hear how long the diode lasts in practice at 400 °C. Dopant rediffusion would be erasing the diode junction at a goodly rate, I fear. Erik -- A friend is a person who knows all about you but likes you just the same. - W.G.P ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
