Quick project boxing for a voltage reference - UK Vintage Radio Repair and Restoration Discussion Forum

The Philpott · 25th Jun 2019, 8:49 pm

Not exactly homebrew as all the work was done before they arrived, but-

1) & 2) An Adafruit 2.048v/4.096v reference chip installed in an Avominor chassis. Three threads had been destroyed in this meter, presumably by overtightening, and there was also external damage. I stripped out all the decent parts including the glass, using the movement to resurrect a skip-find meter, and storing the rest as spares.
The Vref board (visible from the front) is behind a sheet of acrylic. The on-off switch is simply a jump lead (pictured). This has the advantage that poor contact doesn't occur (and would be easily rectifiable if it did) and also the lid of the chosen tin cannot be closed while the instrument is switched on. The voltage of the PP3 power source can be checked via the '500v' and 'COM-NEG' terminals. The Vref voltages are available between the '5V' or '25v' terminals and COM-NEG.

I felt i could justify this conversion of a damaged meter..having rescued a table lamp Avominor from steampunk status previously.

3) & 4) The box from a DC Avominor keeps this Chinese Vref board safe from impact and dust- it's simply screwed onto a thick ply base, using plastic tube cut from the end of fischer wallplugs as stand-off spacers. The box has not had any mods. There is a compartment slot for the batteries. I like the jump lead arrangement- because as it stands this Vref is another that cannot be left switched on with the lid closed. The Duracells are leaving the building very shortly, needless to say!

Dave

25th Jun 2019, 8:49 pm	#1
The Philpott Dekatron Join Date: Aug 2016 Location: Colchester, Essex, UK. Posts: 4,107	Quick project boxing for a voltage reference Not exactly homebrew as all the work was done before they arrived, but- 1) & 2) An Adafruit 2.048v/4.096v reference chip installed in an Avominor chassis. Three threads had been destroyed in this meter, presumably by overtightening, and there was also external damage. I stripped out all the decent parts including the glass, using the movement to resurrect a skip-find meter, and storing the rest as spares. The Vref board (visible from the front) is behind a sheet of acrylic. The on-off switch is simply a jump lead (pictured). This has the advantage that poor contact doesn't occur (and would be easily rectifiable if it did) and also the lid of the chosen tin cannot be closed while the instrument is switched on. The voltage of the PP3 power source can be checked via the '500v' and 'COM-NEG' terminals. The Vref voltages are available between the '5V' or '25v' terminals and COM-NEG. I felt i could justify this conversion of a damaged meter..having rescued a table lamp Avominor from steampunk status previously. 3) & 4) The box from a DC Avominor keeps this Chinese Vref board safe from impact and dust- it's simply screwed onto a thick ply base, using plastic tube cut from the end of fischer wallplugs as stand-off spacers. The box has not had any mods. There is a compartment slot for the batteries. I like the jump lead arrangement- because as it stands this Vref is another that cannot be left switched on with the lid closed. The Duracells are leaving the building very shortly, needless to say! Dave Attached Thumbnails