Products > Test Equipment

New ANENG Q1 9999 Counts ?

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Kleinstein:
The relay may be needed because of the buttons instead of the mechanical switch.  The main purpose is likely to isolate the Ohms current source - also using it for the mV ranges is more like an extra to keep the noise low. For the ohms sense they still need to go through those melf resistors though. It is odd to have both relay contacts in parallel - I would more like expect the two contacts in series if they really mean the CAT rating seriously and not just by Chinese standards.

The soldering on the reference does not look that good - it's likely soldered in the other side. The ICL8069 is kind of a low power TL431 grade reference.

joeqsmith:
At 6 min in the PTC and clamp node I suspect is the drive side for the diode, resistance, capacitance, etc. modes. The high impedance leg is the input. You should hear the relay switch in anytime you change to one of the other modes.

HKJ:
The meter was just as I expected, but I am not sure that bargraph is 100 separate segments, i suspects they are grouped.
It also looks like the meter has two inputs after the relay, one through the PTC one around (This is a fairly common design).

Fungus:

--- Quote from: Kleinstein on June 13, 2018, 04:48:45 pm ---The relay may be needed because of the buttons instead of the mechanical switch.  The main purpose is likely to isolate the Ohms current source - also using it for the mV ranges is more like an extra to keep the noise low.

--- End quote ---

Yep. It looks like it switches in when the probes are an "output" (Ohms, continuity, diode, etc.)

The the PTC should really be before before the relay, but they put the PTC after the range switch in their other meters so nothing new there. It probably doesn't matter, if you're doing something incorrect enough to wreck the range switch then that little PTC probably isn't going to save you.


--- Quote from: Kleinstein on June 13, 2018, 04:48:45 pm ---The soldering on the reference does not look that good - it's likely soldered in the other side.

--- End quote ---

It must be touching somewhere or the meter wouldn't work.

I'd like to give it a wiggle and see what happens.

Fungus:

--- Quote from: HKJ on June 13, 2018, 04:59:18 pm ---It also looks like the meter has two inputs after the relay, one through the PTC one around (This is a fairly common design).

--- End quote ---

The "PTC" path will be for 'output' modes, the other path will be mV - less impedance than the main volts range.

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