how to make a DVA adapter for multimeter

[mrmamiller]

Re: how to make a DVA adapter for multimeter

I know the thread has been going for 3 years, but...

I'm wondering if the capacitor can be a non-polarized type? I have a lot of old electronic parts laying around but not a polarized cap in 2.2mfd/400wvdc. I CAN parallel 3 caps that are non-polarized and come up ~ 2mfd/990VAC. I know I can buy the correct cap online (thanks to a previous link), but I really don't want to spend 20 times the cap price on shipping. I've got all the rest of the crap laying around.

 

[boobie]

Re: how to make a DVA adapter for multimeter

Please read the rules at the top of the forum and start a new one !!! Thank You.

 

[ncpi]

Re: how to make a DVA adapter for multimeter

I know the thread has been going for 3 years, but...

I'm wondering if the capacitor can be a non-polarized type? I have a lot of old electronic parts laying around but not a polarized cap in 2.2mfd/400wvdc. I CAN parallel 3 caps that are non-polarized and come up ~ 2mfd/990VAC. I know I can buy the correct cap online (thanks to a previous link), but I really don't want to spend 20 times the cap price on shipping. I've got all the rest of the crap laying around.

There is no reason you have to have a polarized cap, but the caps you have may have a high enough leakage current that they may not be optimal. My suggestion is buy them from Digi-key (DigiKey Electronics - Electronic Components Distributor). I bought 2 caps and 1 diode and 2 Resistors to build this (including an extra cap and resistor) and the total with shipping was $3.85. It was sent by 1st class mail and Digi-key only charges for actual cost.

Cap: 399-6095-ND CAP ALUM 2.2UF 400V 20% RADIAL ($0.30 each)
Diode: 1N4004-E3/54GICT-ND DIODE GP 400V 1A DO204AL ($0.43 each)
Resistor: CF14JT1M00CT-ND RES 1M OHM 1/4W 5% CARBON FILM ($0.16 each)

The rest of the cost was shipping/tax


Boobie....My opinion here....This is a terrific reference thread, starting a new one really doesn't provide the advantage of being able to look at the old material. I think this one should be an exception to the 3 month rule. I even have it bookmarked/subscribed specifically because it it so useful.

 

[boobie]

Re: how to make a DVA adapter for multimeter

I just read through it and with this one I have to agree with you. There's a lot of info. It should probably be in the top secret files.

 

[ncpi]

Re: how to make a DVA adapter for multimeter

I just read through it and with this one I have to agree with you. There's a lot of info. It should probably be in the top secret files.

I think that would be great Boobie!

 

[ferman]

Re: how to make a DVA adapter for multimeter

can anyone clue me in on what might be wrong? 1st of all let me say that I'm testing this adapter on a running 1974 85hp evinrude. I built adapter per schematic," 1n4004 diode 2.2 uf cap., 1mohm 1/4w resistor." When tested on house current meter reads 167 vdc as it should, or so I am told, but when I check voltage between the brown and brown/yellow wire for 150vdc I only get 16vdc.

 

[ncpi]

Re: how to make a DVA adapter for multimeter

can anyone clue me in on what might be wrong? 1st of all let me say that I'm testing this adapter on a running 1974 85hp evinrude. I built adapter per schematic," 1n4004 diode 2.2 uf cap., 1mohm 1/4w resistor." When tested on house current meter reads 167 vdc as it should, or so I am told, but when I check voltage between the brown and brown/yellow wire for 150vdc I only get 16vdc.

Hi Ferman,
Looks like your DVA is working as it should as it is reading peak AC line voltage correctly. As far as troubleshooting your specific engine issue, I suggest opening a specific thread on that.

 

[ferman]

Re: how to make a DVA adapter for multimeter

Hi Ferman,
Looks like your DVA is working as it should as it is reading peak AC line voltage correctly. As far as troubleshooting your specific engine issue, I suggest opening a specific thread on that.

thanks ncpi. I'm using outboardignition.com's testing procedures for my specific model, but i can take another look.

 

[ko4nrbs]

I realize this is an old thread but I am confused about the value of the capacitor. Is it 2.2uf or 22uf? I've seen both values posted.
Bill

 

[Vic.S]

I realize this is an old thread but I am confused about the value of the capacitor. Is it 2.2uf or 22uf? I've seen both values posted.
Bill

It is 2.2 uF The design was published by Bill Rogers on the ScreamandFly forum in Dec 2003:
He says Re: a different capacitance value, you could go up to maybe 4.7uF, but it will take a little longer for the reading to stabilize (which means more wear on your starter). If you go much less than 2.2uF, it might fail to hold the peak value constant between input pulses.

 

[ko4nrbs]

I got it built and tested in a wall socket and it works. Read about 170 volts on the meter using the DVA.

I used a 3.3 volt electrolytic capacitor rated at 400 volts. It's all I had available for now.
Thanks,
Bill

 

[Dmitriy Balenko]

Hi, I made this device and decided to check the network 220-240 volts 50 Hz. The device burned! Why?

 

[gm280]

Hi, I made this device and decided to check the network 220-240 volts 50 Hz. The device burned! Why?

What part or parts actually smoked?

 

[interalian]

Cap too big? I thought it was supposed to be 2.2uF.

 

[Vic.S]

Cap too big? I thought it was supposed to be 2.2uF.

The 300 ohm resistor limits the charging current when a 22 μF capacitor is used. Otherwise the diode may be damaged.

 

[DouglasW]

I calculated the power consumed by the 300 Ohm resistor and 22 uFD cap to be 30 Watts, with 18 Watts for the resistor. That circuit was not designed to be used with that high a voltage with a 22 uFD cap. Unless the resistor is 20 Watts or more, it will smoke. So will the cap. It should be 2.2 uFD. Even then with 240v applied, the resistor must be 2 watts or larger if this is to be used for more than a few seconds.

Don't forget that the power is squared with a doubling of the voltage So those who got this to work at 120v with small components and 2.2 uFD were experiencing only 1/4 the power that is created at 240v..