The Museum of HP Calculators

HP Forum Archive 01

[ Return to Index | Top of Index ]

41cv charger -what is voltage?
Message #1 Posted by mark french on 21 Mar 1999, 3:37 a.m.

what is voltage of charger for use when charging the nicad pack? and is ac or dc?

      
Re: 41cv charger -what is voltage?
Message #2 Posted by Chuck Ratliff on 21 Mar 1999, 3:57 p.m.,
in response to message #1 by mark french

HP AC adapter/re-charger model 82059B for the CV calls out the following:

INPUT: 90-120_V DC 7_W OUTPUT: 8_V AC 3_W max

Good luck.

      
Re: 41cv charger -what is voltage?
Message #3 Posted by Raul F. Rueda on 22 Mar 1999, 8:46 a.m.,
in response to message #1 by mark french

Output at the chargers has to be 8VAC (not DC), 3W. Now something to take into account: the EURO model works with 230VAC input at 50Hz, which is OK for european countries. But here in Peru, for instance, we use 220VAC at 60Hz (odd?); so, when the Euro Adapter is plugged in, the output goes to 11VAC due to the frequency effect.

            
Re: 41cv charger -what is voltage?
Message #4 Posted by Reinhard Hawel on 22 Mar 1999, 5:34 p.m.,
in response to message #3 by Raul F. Rueda

Nope

The 11V occur because you measured UNLOADED ! My 82066B (Euro) Adapter outputs 12.4V unloaded in Austria. Mains supply is 230V/50Hz.

My 71, 41, 97 and the 82161 work flawlessly with this voltage. Don't forget, that these adapters are simple transformers. The stabilisazion circuits are built into the calculators.

The 8VAC are rated for the load of 3W. I don't believe that the difference between 50->60 Hz does change any important values.

BTW the 82066 is rated for 220V 50Hz (not 230V).

I don't believe that there was any special adapter for Peru or other South-American countries.

                  
Re: 41cv charger -what is voltage?
Message #5 Posted by Raśl F. Rueda on 25 Mar 1999, 9:02 a.m.,
in response to message #4 by Reinhard Hawel

Thanks both Reinhard and Walt for your welcome corrections. "Errarem humanum est".

Yes. Mine is a 82066B Eurocharger, 220VAC, 50Hz. I can't remember when the last time I used this charger was. My battery pack died years ago and I related the voltage rating with some English appliances, I think. Right: the output is 8VAC , 3VA (not watts, and they're not EXACTLY the same).

Measuring this output with a Fluke 83, I got 11.10VAC with no load, at 60Hz. What happened to the 12.5VAC? Well, I measured the inductance of the transformer coils with a BK Precision 875A LCR meter and got 22.3H at the primary and 63.6mH at the secondary. Remember XL=2*pi*f*L ? Well, if the frequency increases from 50 to 60Hz, XL goes up as well, which yields to a reduction in current at the primary (keeping the voltage constant). If this current is reduced, then the magnetic flux is lower, so the induced current at the secondary will be less too. If current is decreased, then the voltage at the seconday will be lower, resulting 11 and not 12.5?

Up to this point I'm not sure wether this thought is right or not. Please correct me if I'm wrong!!!!!!

                        
Re: 41cv charger -what is voltage?
Message #6 Posted by Reinhard Hawel on 25 Mar 1999, 5:35 p.m.,
in response to message #5 by Raśl F. Rueda

You are right.

Our measurements:

my charger 230V/50Hz: 12.4 VAC unloaded yours 220V/60Hz: 11.1 VAC unloadad

I should note that the eurocharger is rated for 2.5VA, not for three. I was inexact in this point. I also wanted to point out in my former post, that it will surely work and all other differences were neglectable in this case. Now a more exact calculation.

I don't have the LCR meter yet, so I haver to use your values, which seem realistic. However there can be significant tolerances, which can make a comparison with measured values completely useless. I therefore refer to your L, values and the Voltage as rated in our countries.

A short calculation shows the difference between the two cases:

secondary yours: XLs=2*pi*60Hz*63.6uH = 23.98 mOhms

mine: XLs=2*pi*50Hz*63.3uH = 19.98 mOhms

primary yours: XLp=2*pi*60Hz*22.3H = 8407 Ohms

mine: XLp=2*pi*50Hz*22.3H = 7006 Ohms

I don't have the value for the copper resistance on your charger, so I have to neglect it. I'm sure that it is much lower than the XL. Please measure. I don't like to take the values of mine. BTW it would be of interest measuring the value of Rcus (Copper res secondary too). This may be considerably high against the XLs and show an important load condition, when the charger is loaded with, say some Ohms. The charger cannot be destroied by shorting the secondary side, as the symbols on the charger show (in german the =OO] sign on the right lower side of the side means "absolut Kurzschlussfest" = "absolutely short circuit proof"). You may have to check this out on your transformer. It could be of interest measuring the short-circuit current or put a load of some Ohms on the transformer. Maybe I could do this in the next days.

I also neglected the inner resistance of the mains supply which can vary much even between two different plugs. In any case it is much lower than XLp.

I primary yours: Ip=220V/8407 Ohms = 32.82 mA

mine: Ip=230V/7006 Ohms = 26.16 mA

NOTE: I think that we should measure the series copper resistances Rs and Rp and calculate the values of Zp and Zs. This will surely give more exact results for this calculation. The other losses a transformer contains (curl current (is that the right word for "Wirbelstrom"?) in the iron) are not that easy to measure and are neglected for this case.

                              
Re: 41cv charger -what is voltage?
Message #7 Posted by Raśl F. Rueda on 26 Mar 1999, 7:19 p.m.,
in response to message #6 by Reinhard Hawel

My charger is labeled "OO" as well. Now, if you have a VARIAC (variable transformer), adjust it to 22 or 23VAC (actually, any voltage between 10 to 15% of the input voltage) and short the output. This will allow you to measure the nominal current rating for the transformer the usual way. I'll try to measure (directly or indirectly) the copper resistance to determine the impedances and pass this info to you.

                              
Re: 41cv charger -what is voltage?
Message #8 Posted by Wayne Brown on 27 Mar 1999, 5:32 p.m.,
in response to message #6 by Reinhard Hawel

I believe the English term for which you're looking is "eddy current."

      
Re: 41cv charger -what is voltage?
Message #9 Posted by Walt Devaney on 22 Mar 1999, 8:36 p.m.,
in response to message #1 by mark french

Either the HP82059 B or D give 12.5VAC out for 120 VAC in with no load. The load from the battery circuit is at most about 25 mA so there is little drop from this value when connected to the battery pack. The equivalent series resistance of the HP82059 into the load is about 11 ohms. All this agrees pretty well with the 3 watt, 8 volt rating. Because the regulator circuit in the 82120A clamps at about 6.7 VDC, you don't have to worry much about the AC voltage into the pack. What you do have to worry about is protecting the calculator, I have seen a couple of fried regulators in dead 82120A's

[ Return to Index | Top of Index ]

Go back to the main exhibit hall