how to make a DVA adapter for multimeter

[Dabbler_E]

Re: how to make a DVA adapter for multimeter

Or do you have the homemade adapter plugged into your regular voltmeter set on DC scale and test as you normally would?

Yes, that's correct, it's hooked to your meter as you use it, so you can see voltage in real time.

One more. When testing for instance the brown wires coming off my stator which is generally considered "positive"? If I use a certain electronic capacitor doesnt it only work in one direction? If that is the case I have to put the red lead to the "positive"wire from the stator, which would it be?

The current coming out of the stator is alternating, but the diode rectifies it, so that current only gets to the capacitor when the charge coming to the red lead is positive. For that reason, it doesn't matter which wire you hook the red lead to -- you'll get readings on the times when that wire is carrying positive charge.

 

[bktheking]

Re: how to make a DVA adapter for multimeter

This thread just doesn't die, LOL. To confirm Bill Rogers design, I tested out mine last night on a Merc stator, pulled over 400 Volts on the meter set to DC, I was impressed.

 

[surrender]

Re: how to make a DVA adapter for multimeter

Thanks everybody, I should have thought about the diode. When I fing the capacitor i'll post results... maybe start another thread

 

[ezeke]

Re: how to make a DVA adapter for multimeter

Thanks everybody, I should have thought about the diode. When I fing the capacitor i'll post results... maybe start another thread

Here's another link you can use: http://cdielectronics.com/downloads/troubleshooting guide/DVA Explained.pdf

 

[Vic.S]

Re: how to make a DVA adapter for multimeter

Here's another link you can use: http://cdielectronics.com/downloads/troubleshooting guide/DVA Explained.pdf

I notice that towards the end of that they state that the DVA adapter has a built in bridge rectifier. I wonder if there would be anything to be gained by using 4 diodes wired as a full wave bridge rectifier in place of the single diode giving only half wave rectification.

 

[surrender]

Re: how to make a DVA adapter for multimeter

Got my capacitator from an HVAC supply house, a 3 micro farad 440 volt for 2 bucks. Worked great, as for the motor not so much, only 99-100 volts output from the stator. removed flywheel and you could see the some evidence of melting on the case. going to get a new/used one local and check at end of week.

 

[vettenuts]

Re: how to make a DVA adapter for multimeter

Will this resister work: 1M Ohm 1W Flameproof Resistor

Don't see a voltage rating and it isn't 1/4 W

 

[wilde1j]

Re: how to make a DVA adapter for multimeter

1W is fine, but voltage rating needs to up ~ 450v.

 

[vettenuts]

Re: how to make a DVA adapter for multimeter

1W is fine, but voltage rating needs to up ~ 450v.

No voltage rating listed, but with a 450 volt capability and 1M ohm, wouldn't that come to less then 1/4 Watt? In other words, wouldn't the higher power capability of 1 Watt handle that voltage?

 

[ezeke]

Re: how to make a DVA adapter for multimeter

No voltage rating listed, but with a 450 volt capability and 1M ohm, wouldn't that come to less then 1/4 Watt? In other words, wouldn't the higher power capability of 1 Watt handle that voltage?

Are we really hanging up the project on a thirty cent part? http://shop.vetcosurplus.com/catalog/product_info.php?products_id=8180

OK, make fifteen cents. http://www.basicmicro.com/Resistor-1MEG-Ohm-14-Watt_p_107.html

 

[guitman32]

Re: how to make a DVA adapter for multimeter

I built an adapter per Bill's schematics.

Noticing about a .3-.4 voltage drop in the DVA reading vs the comparable meter reading without the DVA adapter as tested on several 1.5, 12 and 18 volt batteries.

For example, tested an 18V drill battery, fully charged. 18.109 volts with DVA, 18.308 with the multimeter set on VDC no DVA.

I attribute this to the voltage drop across the diode, BUT wanted to voice this to the community to see if this is normal.

 

[aaasnapper]

Re: how to make a DVA adapter for multimeter

Yes, I made a DVA today and found the same voltage drop of about 0.3V DC on a 1.5V battery.
I believe a voltage drop of 0.3V DC to be normal loss over those components as well as the dodgi soldering job i have done.

 

[guitman32]

Re: how to make a DVA adapter for multimeter

Alternative design-very sturdy:

 

[Lostfisher]

Re: how to make a DVA adapter for multimeter

The 2.2 uf @ 450v and the diode are two different things? I already soldered 2 diodes on the DVA.

 

[Vic.S]

Re: how to make a DVA adapter for multimeter

The 2.2 uf @ 450v and the diode are two different things? I already soldered 2 diodes on the DVA.

look the diagrams in previous posts

D1 is the diode. When soldering take care not to heat the diode by holding the wires with pliers and soldering quickly.
C1 is the 2.2 μF capacitor
R1 is the 1 MΩ resistor

 

[Lostfisher]

Re: how to make a DVA adapter for multimeter

Is there aother type of capacitor that would work. the highest volt that i can find is 350.

 

[durban]

Re: how to make a DVA adapter for multimeter

can i use a 1/2 watt resistor instead of a 1/4 watt resistor my supplier tells me it wont make any difference as he doesn't have it in stock the 1/2 watt resistor will handle the current , is this true

 

[ncpi]

Re: how to make a DVA adapter for multimeter

can i use a 1/2 watt resistor instead of a 1/4 watt resistor my supplier tells me it wont make any difference as he doesn't have it in stock the 1/2 watt resistor will handle the current , is this true

1/2W is fine, it will handle twice the power dissipation - no functional change.

 

[Crosbyman]

Re: how to make a DVA adapter for multimeter

Lessons In Electric Circuits -- Volume III (Semiconductors) - Chapter 3


see article on DVA .(peak detector) ..also read somewhere if your actually read the AC from the stator and multipli by 1.41 it should about equate about what you will measure in DC from the DVA adapter which is just a AC to DC converter via the diode rectifying half the AC wave to store it in the capacitor.


the article is for 5 vac ...so use about recommended parts values for your expected measurements

 

[durban]

Re: how to make a DVA adapter for multimeter

thank you crosbyman & ncpi the site you gave me is very helpful too . cheers