they would not be as well matched as if they were on the same chip On Sat, Sep 12, 2015 at 3:12 PM, Dave M <[email protected]> wrote:
> I realize that better references are available. > > I was thinking of resurrecting a long-defunct Fluke 731 that I have in the > garage. The reference IC is bad in it, and (1) I don't want to throw it > away without a meager attempt at repair, and (2) I don't want to spend a > lot of money on it because it's in pretty bad physical condition. > > I was hoping that someone could lend a touch of advice on those old > references. I have a few 1N827A reference zeners, and a washtubful of > transistors. Maybe something could be cobbled together that would get the > 731 back in operation. Maybe not to original specs, but close, which is > better than nothing. > > Thanks for your reply, > Dave M > > > > > Jack Mcmullen via volt-nuts wrote: > >> Just thinking why would you reinvent a transistor/zener reference >> when the industry's voltage reference chips are in the $2.00 or less >> single quanities with performance far exceeding anything previously >> available in discrete components?? >> >> >> >> >> -----Original Message----- >> From: Dave M <[email protected]> >> To: FEBO Volt-Nuts <[email protected]> >> Sent: Sat, Sep 12, 2015 1:58 pm >> Subject: [volt-nuts] Making a Reference IC >> >> >> >> >> I was looking at the schematics for the Fluke 731 and 732 voltage >> references. these, and several other brands and models of voltage >> references, use the same or similar reference ICs as their basis. The >> reference ICs are a Zener/NPN transistor pair on a single substrate. >> >> Please view in a fixed-width font such >> as Courier. >> >> | >> | >> C | >> | >> | >> | >> |---- >> | B >> /| >> / | >> E | >> | >> +--------------- >> | >> /------/ >> / >> ------ >> | >> | >> >> Just thinking... would it be possible to make a reference with similar >> characteristics with discrete components (a low tempco Zener and a >> transistor)? They would likely have to be closely coupled thermally >> and >> maintained at a constant temperature within an oven or by a peltier >> device. >> >> What criteria would apply to the selection of the parts? >> >> Dave M >> > > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips* _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
