| Electronics > Beginners |
| zener reference instability |
| << < (3/3) |
| nnills:
I put the breadboard in a esd bag with some foam in the opening(to stop airflow). It is now stable to 100 uV!(over 1 hour) :) |
| iMo:
Have you coupled the zener and the transistor thermally? |
| Andreas:
--- Quote from: imo on March 11, 2019, 04:49:02 pm ---It looks like the LM358 does not like that wiring :) --- End quote --- No Op-Amp likes 100nF (C3) across the output without furhter measures. (see my LTZ1000 cirquit with a additional series resistor for the negative input and a additional capacitor from Output to negative input of the OP) --- Quote from: imo on March 11, 2019, 06:50:44 pm ---Have you coupled the zener and the transistor thermally? --- End quote --- Even then there will be some T.C. For a good compensation between zener and VBE you will have to increase the zener voltage to 5.6-6.2 (around 5.9) V with best regards Andreas |
| IconicPCB:
What Andreas said ... Go with a slightly higher zener voltage and then insert a low value resistor ( in the order of tens of ohms between the zener and the transistor base. Adjust the resistance for prefered zero tempco temperature ( say room temperature?) |
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