Electrochemistry: Liquid Power Resistor for 2000VAC
in [Design]
|
Prev: animal survey
Next: Friends important message for you
From: D from BC on 12 Mar 2010 12:54 I'm setting up a test circuit and I need a 100k resistor that can handle 2000VAC for a few seconds. I was going to run off to the local surplus shop but got the idea of making a liquid resistor. Saves a trip. I added some salt to water and got 100kohm. Copper electrodes (all I got at the moment). Question is... Will this stay 100kohm +/- 10kohm up to 2000VAC? My circuit only needs to run for 5 seconds. iows...Does salty water resistance vary with voltage?
From: Jon Slaughter on 12 Mar 2010 13:02 D from BC wrote: > I'm setting up a test circuit and I need a 100k resistor that can > handle 2000VAC for a few seconds. > > I was going to run off to the local surplus shop but got the idea of > making a liquid resistor. Saves a trip. > > I added some salt to water and got 100kohm. Copper electrodes (all I > got at the moment). > > Question is... Will this stay 100kohm +/- 10kohm up to 2000VAC? > My circuit only needs to run for 5 seconds. > > iows...Does salty water resistance vary with voltage? Why not experiment with it since you already have the setup? Try putting a 100k res in series and measure the voltage. Sweep up to 200VAC and see if the volage devates from 100VAC at the divider. I imagine if the liquid gets hot the resistance will change so you might try an ice bath. You could then try with and without the ice bath and find the deviation to get some temperature dependence relation.
From: Jim Thompson on 12 Mar 2010 13:04 On Fri, 12 Mar 2010 09:54:46 -0800, D from BC <myrealaddress(a)comic.com> wrote: >I'm setting up a test circuit and I need a 100k resistor that can handle >2000VAC for a few seconds. > >I was going to run off to the local surplus shop but got the idea of >making a liquid resistor. Saves a trip. > >I added some salt to water and got 100kohm. Copper electrodes (all I got >at the moment). > >Question is... Will this stay 100kohm +/- 10kohm up to 2000VAC? >My circuit only needs to run for 5 seconds. > >iows...Does salty water resistance vary with voltage? Trying out another "natural selection" experiment ?:-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: John Larkin on 12 Mar 2010 13:12 On Fri, 12 Mar 2010 12:02:46 -0600, "Jon Slaughter" <Jon_Slaughter(a)Hotmail.com> wrote: >D from BC wrote: >> I'm setting up a test circuit and I need a 100k resistor that can >> handle 2000VAC for a few seconds. >> >> I was going to run off to the local surplus shop but got the idea of >> making a liquid resistor. Saves a trip. >> >> I added some salt to water and got 100kohm. Copper electrodes (all I >> got at the moment). >> >> Question is... Will this stay 100kohm +/- 10kohm up to 2000VAC? >> My circuit only needs to run for 5 seconds. >> >> iows...Does salty water resistance vary with voltage? > >Why not experiment with it since you already have the setup? Try putting a >100k res in series and measure the voltage. Sweep up to 200VAC and see if >the volage devates from 100VAC at the divider. > >I imagine if the liquid gets hot the resistance will change so you might try >an ice bath. You could then try with and without the ice bath and find the >deviation to get some temperature dependence relation. > > Copper will be electrolyzed into solution and the resistance will drop. And bubbles will form on the electrodes and resistance will increase! Neither happens fast at low currents. But the dissipation is only 40 watts for 5 seconds. A string of, say, ten or so 2-watt carbon film resistors would work fine. John
From: D from BC on 12 Mar 2010 13:14
In article <7g0lp5t9t6jpb92uvtaj85hu29ebg8s89i(a)4ax.com>, To-Email-Use- The-Envelope-Icon(a)My-Web-Site.com says... > > On Fri, 12 Mar 2010 09:54:46 -0800, D from BC > <myrealaddress(a)comic.com> wrote: > > >I'm setting up a test circuit and I need a 100k resistor that can handle > >2000VAC for a few seconds. > > > >I was going to run off to the local surplus shop but got the idea of > >making a liquid resistor. Saves a trip. > > > >I added some salt to water and got 100kohm. Copper electrodes (all I got > >at the moment). > > > >Question is... Will this stay 100kohm +/- 10kohm up to 2000VAC? > >My circuit only needs to run for 5 seconds. > > > >iows...Does salty water resistance vary with voltage? > > Trying out another "natural selection" experiment ?:-) > > ...Jim Thompson lol :) |