Volts D.C. panel meter for B+

btran · 19th December 2009, 04:19 PM

I have builted the tubelab SE and I just wonder how to put in the Volts D.C. panel meter to monitor the B+ voltage. Advices are greatly appreciated!

Regards,

Binh

Glowbug · 19th December 2009, 05:07 PM

Wire it in parallel...just like you'd test it with a DMM

Good meters are available from places like Surplus Sales of Nebraska or Mouser...

btran · 19th December 2009, 08:51 PM

I did a test which hook it up the Simpson (ohms per volt 600 DCV) with a power supply 9 DCV at 0-25 mA and the needle went all the way. I think it needs a circuitry to do a job.

dhaen · 19th December 2009, 09:02 PM

Probably the meter is just an ammeter and it expects a series resistor.
Look for a marking that gives the FSD (Full Scale Deflection) current. You can use this with the meter resistance to calculate the value of resistor required.
This link: RADIO AMATEUR EXAM
explains far better than I can.

Steerpike · 19th December 2009, 10:42 PM

Something I'd do: put a Zener diode of around 100V to 200V inseries with the meter and its resistor. That way you shift the meter zero by 100V or 200V or whatever you want. Then your meter scale runs from 100V up to 250V ( or 200V-350V) or whatever you want, instead of 0v up to 250V. This give a more acurate expanded scale, since measuring below 100V is not really useful.

btran · 20th December 2009, 08:58 PM

The volt panel meter Simpson I have is not directed hook up and it needs the 6 meg-ohms resistor in series to be function right. I just wonder would it change the B+ if I have it in parallel with R30 and what are the effects? Schematic

dhaen · 20th December 2009, 09:22 PM

6Meg is very high, you must have a sensitive meter. What is the FSD current rating?

In any event, connecting the whole network (meter + series resistor) in parallel with R30 is correct. It will not affect the voltage in any measurable way.

kevinkr · 20th December 2009, 09:32 PM

Quote:

Originally Posted by btran

The volt panel meter Simpson I have is not directed hook up and it needs the 6 meg-ohms resistor in series to be function right. I just wonder would it change the B+ if I have it in parallel with R30 and what are the effects? Schematic

If this is the same meter you connected across the supply previously without the required series resistor it is highly likely that the meter has been damaged by the experience. I would test the meter with an appropriate series resistor before making any plans to install it permanently. (Most likely it is a sensitive micro-ammeter and it has been exposed to a current many orders of magnitude greater than it was designed for.) Hopefully you have another meter you can install.

btran · 20th December 2009, 09:46 PM

I try to find the data for my meter but couldn't find it. On the meter I found these info.

1000 ohms per volt
Simpson Electric Co. Elgin , Ill 60120 U.S.A.

Model 324 NO.

The Volt scale is : 0 200 400 600
0 100 200 300

I want to use it with 600 volt scale and by my calculation that I have to use 600,000 ohms or 600K, but it couldn't handle when I tried to measure 9V battery.
I just used the 2.2meg then it seem work and finally I use 6meg and tried with the power supply at 600 volts to test it. If you see some thing wrong please correct me.

btran · 20th December 2009, 10:06 PM

Here is the picture of my meter

19th December 2009, 04:19 PM	#1
btran diyAudio Member Join Date: Jul 2009 Location: Sugar land, Texas	Volts D.C. panel meter for B+ I have builted the tubelab SE and I just wonder how to put in the Volts D.C. panel meter to monitor the B+ voltage. Advices are greatly appreciated! Regards, Binh

19th December 2009, 05:07 PM	#2
Glowbug diyAudio Member Join Date: Feb 2006 Location: Hillsborough, NC/McLean, VA	Wire it in parallel...just like you'd test it with a DMM Good meters are available from places like Surplus Sales of Nebraska or Mouser... __________________ Jim J.

19th December 2009, 10:42 PM	#5
Steerpike diyAudio Member Join Date: Jan 2006 Location: Johannesburg, South Africa	Something I'd do: put a Zener diode of around 100V to 200V inseries with the meter and its resistor. That way you shift the meter zero by 100V or 200V or whatever you want. Then your meter scale runs from 100V up to 250V ( or 200V-350V) or whatever you want, instead of 0v up to 250V. This give a more acurate expanded scale, since measuring below 100V is not really useful. __________________ Steerpike's Toybox

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19th December 2009, 08:51 PM	#3
btran diyAudio Member Join Date: Jul 2009 Location: Sugar land, Texas	I did a test which hook it up the Simpson (ohms per volt 600 DCV) with a power supply 9 DCV at 0-25 mA and the needle went all the way. I think it needs a circuitry to do a job.

19th December 2009, 09:02 PM	#4
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Probably the meter is just an ammeter and it expects a series resistor. Look for a marking that gives the FSD (Full Scale Deflection) current. You can use this with the meter resistance to calculate the value of resistor required. This link: RADIO AMATEUR EXAM explains far better than I can.

20th December 2009, 08:58 PM	#6
btran diyAudio Member Join Date: Jul 2009 Location: Sugar land, Texas	The volt panel meter Simpson I have is not directed hook up and it needs the 6 meg-ohms resistor in series to be function right. I just wonder would it change the B+ if I have it in parallel with R30 and what are the effects? Schematic

20th December 2009, 09:22 PM	#7
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	6Meg is very high, you must have a sensitive meter. What is the FSD current rating? In any event, connecting the whole network (meter + series resistor) in parallel with R30 is correct. It will not affect the voltage in any measurable way.

20th December 2009, 09:46 PM	#9
btran diyAudio Member Join Date: Jul 2009 Location: Sugar land, Texas	I try to find the data for my meter but couldn't find it. On the meter I found these info. 1000 ohms per volt Simpson Electric Co. Elgin , Ill 60120 U.S.A. Model 324 NO. The Volt scale is : 0 200 400 600 0 100 200 300 I want to use it with 600 volt scale and by my calculation that I have to use 600,000 ohms or 600K, but it couldn't handle when I tried to measure 9V battery. I just used the 2.2meg then it seem work and finally I use 6meg and tried with the power supply at 600 volts to test it. If you see some thing wrong please correct me.

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