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Vintage DC kilovolt meter - wiring multiplier resistors - kilovoltmeter3views.jpg (1/1)
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Vintage DC kilovolt meter - wiring multiplier resistors - kilovoltmeter3views.jpg (1/1)
On Thu, 02 Sep 2010 21:31:25 +0100, glutinous
wrote: On the image the meter says "FS 254V" or something like that. Exactly what is the number, where is the decimal point (if there is on)? This will be the full scale voltage reading, most likely. I'd connect the bare meter to a variable AC source (start at a very low voltage, perhaps a volt or so) and see what reading, and current is drawn by this meter. Also, clearly the meter was salvaged from something else, so I suspect that what you have is something that was kobbled together by a hobiest like Jon, designed to kill the unwary. I'd be very, very careful about applying more than a few hundred volts to it. |
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Vintage DC kilovolt meter - wiring multiplier resistors - kilovoltmeter3views.jpg (1/1)
On Fri, 03 Sep 2010 08:34:34 -0400, PeterD wrote:
On Thu, 02 Sep 2010 21:31:25 +0100, glutinous wrote: On the image the meter says "FS 254V" or something like that. Exactly what is the number, where is the decimal point (if there is on)? This will be the full scale voltage reading, most likely. I'd connect the bare meter to a variable AC source (start at a very low voltage, perhaps a volt or so) and see what reading, and current is drawn by this meter. Also, clearly the meter was salvaged from something else, so I suspect that what you have is something that was kobbled together by a hobiest like Jon, designed to kill the unwary. I'd be very, very careful about applying more than a few hundred volts to it. Thank you very much for the reply, Peter. There is no decimal point, it's: F.S. 254V. Since this is near as dammit to the UK mains voltage, I'd rather thought that was its reference point. I'd also assumed that the meter was AC (hence the 'calibrated at 50~') but supposed that in use it was intended to be fed via rectification: though on opening the box there is none. The Jacob's Ladder I referred to is built and functions well, using (and I always get a childish pleasure out of saying this) a 10kv FART transformer from a neon rig. I was thinking of doing something along the lines you more precisely suggest, as against just whacking the full 10kv through the larger resistor just to see what happened... Standing well back and with a camcorder running, o.c. ... |
#4
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Vintage DC kilovolt meter - wiring multiplier resistors -kilovoltmeter3views.jpg (1/1)
On Sat, 04 Sep 2010 11:28:23 +0100, glutinous wrote:
On Fri, 03 Sep 2010 08:34:34 -0400, PeterD wrote: On Thu, 02 Sep 2010 21:31:25 +0100, glutinous wrote: On the image the meter says "FS 254V" or something like that. Exactly what is the number, where is the decimal point (if there is on)? This will be the full scale voltage reading, most likely. I'd connect the bare meter to a variable AC source (start at a very low voltage, perhaps a volt or so) and see what reading, and current is drawn by this meter. Also, clearly the meter was salvaged from something else, so I suspect that what you have is something that was kobbled together by a hobiest like Jon, designed to kill the unwary. I'd be very, very careful about applying more than a few hundred volts to it. Thank you very much for the reply, Peter. There is no decimal point, it's: F.S. 254V. Since this is near as dammit to the UK mains voltage, I'd rather thought that was its reference point. I'd also assumed that the meter was AC (hence the 'calibrated at 50~') but supposed that in use it was intended to be fed via rectification: though on opening the box there is none. The Jacob's Ladder I referred to is built and functions well, using (and I always get a childish pleasure out of saying this) a 10kv FART transformer from a neon rig. I was thinking of doing something along the lines you more precisely suggest, as against just whacking the full 10kv through the larger resistor just to see what happened... Standing well back and with a camcorder running, o.c. ... It looks to me as if the middle "thing" is a pushbutton. Is that right? In that case, it looks as if it would have been used to short out the resistor (assuming that the lead went to the red terminal) to give a scale multiplier. In no way would that instrument ever have read 25kV directly. It simply doesn't have enough terminal insulation to prevent flashover at anything above 1kV or so (probably 600v). More likely it would have read the output voltage from a variac. That voltage would have fed a step-up transformer and rectifier, giving 0-25kV DC (approximately). Personally, I would start with low AC voltages fed via a resistor and see what it reads. If I'm right it will give fsd at about 250vAC - but start a lot lower than that. -- Mick (Working in a M$-free zone!) Web: http://www.nascom.info Filtering everything posted from googlegroups to kill spam. |
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Vintage DC kilovolt meter - wiring multiplier resistors - kilovoltmeter3views.jpg (1/1)
On Thu, 02 Sep 2010 21:31:25 +0100, glutinous wrote:
Firstly, it's a moving iron meter, and secondly, that resistor looks like it might be the multiplier so it can read 254Vac. Is it not connected? |
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Vintage DC kilovolt meter - wiring multiplier resistors - kilovoltmeter3views.jpg (1/1)
On Tue, 07 Sep 2010 17:51:06 +0800, Ross Herbert
wrote: On Thu, 02 Sep 2010 21:31:25 +0100, glutinous wrote: Firstly, it's a moving iron meter, and secondly, that resistor looks like it might be the multiplier so it can read 254Vac. Is it not connected? Thanks for the reply. Nope, res. not connected. As someone else mentioned, it looks like someone was experimenting with multipliers... |
#7
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Vintage DC kilovolt meter - wiring multiplier resistors - kilovoltmeter3views.jpg (1/1)
On 06 Sep 2010 21:09:48 GMT, mick wrote:
On Sat, 04 Sep 2010 11:28:23 +0100, glutinous wrote: On Fri, 03 Sep 2010 08:34:34 -0400, PeterD wrote: On Thu, 02 Sep 2010 21:31:25 +0100, glutinous wrote: On the image the meter says "FS 254V" or something like that. Exactly what is the number, where is the decimal point (if there is on)? This will be the full scale voltage reading, most likely. I'd connect the bare meter to a variable AC source (start at a very low voltage, perhaps a volt or so) and see what reading, and current is drawn by this meter. Also, clearly the meter was salvaged from something else, so I suspect that what you have is something that was kobbled together by a hobiest like Jon, designed to kill the unwary. I'd be very, very careful about applying more than a few hundred volts to it. Thank you very much for the reply, Peter. There is no decimal point, it's: F.S. 254V. Since this is near as dammit to the UK mains voltage, I'd rather thought that was its reference point. I'd also assumed that the meter was AC (hence the 'calibrated at 50~') but supposed that in use it was intended to be fed via rectification: though on opening the box there is none. The Jacob's Ladder I referred to is built and functions well, using (and I always get a childish pleasure out of saying this) a 10kv FART transformer from a neon rig. I was thinking of doing something along the lines you more precisely suggest, as against just whacking the full 10kv through the larger resistor just to see what happened... Standing well back and with a camcorder running, o.c. ... It looks to me as if the middle "thing" is a pushbutton. Is that right? In that case, it looks as if it would have been used to short out the resistor (assuming that the lead went to the red terminal) to give a scale multiplier. In no way would that instrument ever have read 25kV directly. It simply doesn't have enough terminal insulation to prevent flashover at anything above 1kV or so (probably 600v). More likely it would have read the output voltage from a variac. That voltage would have fed a step-up transformer and rectifier, giving 0-25kV DC (approximately). Personally, I would start with low AC voltages fed via a resistor and see what it reads. If I'm right it will give fsd at about 250vAC - but start a lot lower than that. I'd rather figured that whacking 10kv across it wouldn't be very sensible! When I first made the Jacob's Ladder, I just connected the rod terminals to the wood of the box I was using, just to see if the kit worked. It did: the carbonised track across the wood was unmistakable (I can't remember what I then obtained is called now, but it's transluscent insulating board). Even if this meter could take it, I wouldn't be very happy about having 10kv so close to the outside of the box, just the other side of a bit of glass! I was trying to think how I could put a reduced voltage across it (via a resistor). I just remembered I have a 240 to 110 travel transformer, so I'll give that a go. Thanks for the observations! |
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