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Full Version: Power Supply Instead of HP82033A Battery Pack???
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I have several devices that use the HP82033A battery pack (HP82143A/HP82161A/HP82162A,etc.) I was wondering if I couldn't just use a good 5V DC regulated power supply. (I know this makes it a little less portable, but I can't remember the last time I used them that way.) Some of these have output ripple as low as 5mV. Does anyone know if this will cause any problems? I don't know how sensitive the HP devices are to that. Am I going to be better severed by continuing to rebuild the battery packs as they die off?

A long time ago someone told me about about something called a "Power Base" that fit right into the battery compartment. I thought he said it was made by a company called Asoma, but I couldn't find anything about it. In any case it sounded like a dedicated supply, so I was hopeful.

Any info would be appreciated.

You should be aware of the high peak currents these devices can draw. If your source has a considerable amount of inner resistance, you could cause significant voltage drops at the battery terminals.

Especially the cassette drive with its two motors is suspectible to this behaviour. I remember, some people called the cassette drive a real accu killer because of the peak currents. This was a problem with accus 10 years ago. I replaced my accus with special accus for model cars (I believe Panasonic Hi-Amp) and had never problems after that. Additionally the capacity was somewhat higher.

I believe the printers are also a problem because of the DC-DC converter and the fast changing load conditions (all "needles" burning/none burning. This is no easy task for a power supply.

As a resume, I say you should check the ripple when loaded with changing loads. It's very probable, that the load reactions of the source can really disturb the hp devices. Also you lose a huge capacitor with the accus.

Ni-Cd's are capable of supplying large currents with little reduction in supply voltage. I checked the specifications of the devices mentioned, and the only thing given was consumption when the unit was just sitting there, doing nothing (1.7 watts, or 340 mA). For small periods of time, when the motors spool up and are stopped, large currents (> 1 Amp) are likely. It should be possible to build a supply using a high current AC/DC converter (> 3 Amps) coupled with a very large capacitor. The capacitor will assist with reducing the voltage ripple, but more importantly, will assist with the instantaneous high current demands of motors. If I get around to it, I will try and measure the operating currents of these devices.

I have a cassette drive modified to take power from 4 D alkaline cells. I had to replace the battery holder because the contacts were not good enough, and voltage drop was occuring across them at times of high current draw.

The Cassette drive appears to have sustained demand for high power (i.e. high current).

Note that 4xD cells have a peak voltage of 4*1.7 = 6.8 V compared with 4.8 from the normal pack.

(I have no idea if there is any additional gubbings inside my drive to help it cope with 6.8 V or if the person who did this mod simply connected it internally (although there is at least a diode as the voltage does NOT appear at the battery terminals inside the case).

Are you sure there is a diode? Maybe the internal battery contacts have been disconnected. Will the unit run off of the standard battery mounted inside the compartment?

Also, by the way, the cassette drive must be able to handle the voltage of Ni-Cd's under charge, since the battery can be charged at the same time the drive is being used. I would estimate that the charging voltage is close to 1.5 volts per cell, or 6.0 volts for the total battery.

I am sure now :-)

I'm charging the nicads through this drive and the unit works as expected without the batteries connected.

One other possibility is that the battery socket switches the nicads out of circuit when connected (which means that the charger would also charge nicads in the battery pack Cool!

If I get some D size nicads I might check it out. And at 4000mAH they'd provide a nice charge :-)