[volt-nuts] Voltage Reference Mini-Oven

[WarrenS]

Using a circuit similar to
http://www.febo.com/pipermail/volt-nuts/attachments/20110903/b7da2eca/attachment-0001.gif

A 10 reference standard can be built so that there are only TWO really 
critical parts that limit its performance.
The reference  Zener and the 5/3 gain matched resistors.
The rest just takes careful analog design considerations.
The way I hope to remove the resistor matching limitation is to do that part 
digital.

As far as more details on the Mini-Oven, nothing else to say. It is just 
three small parts "Taped" together.
One is the device to be controlled, one is the heater and the last is the 
temperature sensor. Same as any oven, just smaller.
I don't know how this mini-oven would apply to a standard cell.

ws

*******************
zbigniew169 wrote:
I would be appreciate if You will send some details concerning construction 
of Your mini-oven.

*******************
m k m1k3k1 at hotmail.com wrote

Hi Warren,

That does seem a very simple way to get the diode at a steady temp, but then 
you need to keep the rest steady to stop all the other uncertainties 
swamping the nice steady diode you have just created.

******************

> From: warrensjmail-one at yahoo.com
>
> It is well known that by changing the nominal operating current of a 1N825 
> type reference diode, that its voltage turn over temperature point can be 
> moved.
> Usually the turn over temperature can be set to the nominal operating 
> temperature,  there by giving a Zero TC reference voltage over a limited 
> temperature range.
> For the parts I'm testing, the voltage changes less than 0.1 PPM with a 5 
> deg F temperature variation, and 1PPM over a 20 deg F range when the zero 
> TC current is set for room temperature.
> Not bad, but being an extreme Volt Nut, I always want to do better.
>
> Two ways to make it better, Add an X^2 (second order) temperature 
> compensator or put the reference in an oven.
>
> What I did was make a very simple Mini-Oven using an 1N825, a glass 
> thermister & a 1/4 resistor,
> all heat shrink together  in a small package about the size of a 1 watt 
> resistor.
> Now by Appling about 1/8 W nominal power to the resistor from a simple 
> temperature controller, the thermistor can be held at a constant 
> Temperature.
> This allows setting it up so that normal temperature changes have true 
> ZERO effect on the zero TCed zener voltage.
> Next thing I want to make is a simple times 8/5 digital gain amp so that 
> the gain resistors will have no effect when amplifying the 6.25x volt 
> zener  up to 10.000000 Volts.
> (or times 10/7 for use with other types of voltage references)
>
> ws
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.