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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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7th Sep 2021, 8:31 pm | #1 |
Triode
Join Date: Sep 2017
Location: Preston, Lancashire, UK.
Posts: 28
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AVO Model 8 Mk 7 question
Hi,
I am trying to find out what current you get across the terminals of an AVO Model 8 Mk 7 in the resistance x1 ohm range. I have checked a Mk 6 and get 73.5mA, I am assuming that the a Mk 7 would be similar but don't have both circuits so can't confirm. If anyone has a Mk 7 handy and could do a quick check I would much appreciate it. Thanks Chris |
7th Sep 2021, 8:59 pm | #2 |
Octode
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,813
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Re: AVO Model 8 Mk 7 question
Chris,
The circuit diagram of the Model 8 Mark 7 in attached. What are you using to measure the current at the terminals? The resistance of the measuring device will have an effect on what you measure. If you have several Avometers, a Model 40, for example, would give you a lower resistance on its current ranges than a Model 8. A digital multimeter will have around 1 ohm across the terminals on the 300mA range. PMM |
7th Sep 2021, 10:09 pm | #3 |
Triode
Join Date: Sep 2017
Location: Preston, Lancashire, UK.
Posts: 28
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Re: AVO Model 8 Mk 7 question
PMM,
I had used used a Fluke 87v, admittedly I know it will have an effect but hadn't looked to see how much. I am just trying to get an idea of the value to justify the use of a safety ohmmeter on a 2-3 ohm circuit which is current sensitive. Chris |
8th Sep 2021, 4:08 pm | #4 |
Pentode
Join Date: Mar 2007
Location: Croydon, London, UK.
Posts: 111
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Re: AVO Model 8 Mk 7 question
Hi, you do not get current across the terminals only voltage, on the X1 ohms range the Avo will supply 75m/a
Mike |
8th Sep 2021, 5:21 pm | #5 |
Pentode
Join Date: Mar 2007
Location: Croydon, London, UK.
Posts: 111
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Re: AVO Model 8 Mk 7 question
I should also have said it is 75 m/a into a short circuit and a terminal voltage of approximately 1.5 volts depending on the cell’s internal resistance
Mike |
9th Sep 2021, 6:41 pm | #6 |
Triode
Join Date: Sep 2017
Location: Preston, Lancashire, UK.
Posts: 28
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Re: AVO Model 8 Mk 7 question
Thanks a lot guys that should give me enough to go on
Chris |