Multimeter Calibration

[hpotter]

Yep, anologue meters are easier to understand for many and are part of the ciriculum for budding engineers (including how they work).

The only other point I'd say Arf is that if you change your senario above to volts, not ohms, then your meter says 12v at the PIR, but mine says 10v. Not much in it as you say......

[arfur mo]

Yep, anologue meters are easier to understand for many and are part of the ciriculum for budding engineers (including how they work).

The only other point I'd say Arf is that if you change your senario above to volts, not ohms, then your meter says 12v at the PIR, but mine says 10v. Not much in it as you say......

agreed, that scenario was very common on (even back then) on the mains powered panels,

i was luckier than most as that my older brother was apprentice trained in radio and tv servicing, so he taught me the correct proceedures using his beloved and expensive AVO8 bench meter, the defacto meter of the time.

so i was drilled into testing the leads, checking they were not damaged, always setting the stops before starting any reading and between readings, set to highesst volt range BEFORE connecting the meter to any unkown potentials and so on, otherwise you could blow the middle clean out of the movement no probs and a tad expensive to get fixed

back when i first started (sh^t - is it that long ago), i worked for Burgots Alarms, their panels at that time unusually were all based on a mains transformer in the panel, backed up by a Ever Ready HP1 dry cell battery (hence the bridged load test rig). zones were called 'feed & return' i.e. 12 volts fed out an returned back to the panel.

we were issued the companies 'minitest' swing neadle meters once you passed your grade 2 written and practical tests. they had a 1 amp max DC range. but a real good bit of kit if you got hold of a non abused or new one - and then you did not lend it to anybody else.

most meters had a hard life from engineers, despite reasonable ongoing training many engineers had no real respect for them, bad part of being 'free' i suppose. but is a strange attitude as imo the test meter is as important as a gun is to a soldier.

when Chubbs bought out Burgot and Rely-a-Bell it was horror of horrers time, RAB systems like many used 'end of line' batteries, battery powered controls, and SCB's which had 5 x 'QS' cells. that was a shock to the system i can tell you. EOL batts were usually in the gents on sites, shops and offices, or along side the panel on most domestics, so on commercials you got your steps up to test them. if you changed them the most convenient place to lodge batteries while swapping them over was on the systern box. i lost count how many calls from irate clients nearly brained by 3 x 'O' flagg cells dropping into the pan when they pullled the chain later

regs

alan