[sci.electronics] This is really twisted

hobbit@topaz.rutgers.edu (*Hobbit*) (04/22/89)

I just opened up what porports to be a battery charger for some unknown
kind of radio.  It's a smallish box with a holder on top that has two little
spring-loaded pins down in the well, so you drop the radio in and it starts
charging.  Inside are what you'd expect, a transformer, bridge, a cap, a
regulator, and then it gets seriously weird.  Over at the other end of the 
PCB are two 28-pin DIPs and a crystal.  Now, since when does a lousy battery
charger need serious logic?!  Naturally, my brandy-new NTE book *doesn't*
cross these chips.   The charger's called "Smart Charger" [haw!!] and is made
by Alexander Mfg, Mason City Iowa.

The chips are:

        MSM5842-19RS      "OKI" in a diamond logo
        ADC0808CCN        National, I think

The negative side of the battery pins is fed off three ganged pins of the
ADC0808.  Anyone know what these chips are?  This whole picture is seriously
weird....

_H*

larry@kitty.UUCP (Larry Lippman) (04/23/89)

In article <Apr.21.21.19.36.1989.3812@topaz.rutgers.edu>, hobbit@topaz.rutgers.edu (*Hobbit*) writes:
> I just opened up what porports to be a battery charger for some unknown
> kind of radio.  It's a smallish box with a holder on top that has two little
> spring-loaded pins down in the well, so you drop the radio in and it starts
> charging.  Inside are what you'd expect, a transformer, bridge, a cap, a
> regulator, and then it gets seriously weird.  Over at the other end of the 
> PCB are two 28-pin DIPs and a crystal.  Now, since when does a lousy battery
> charger need serious logic?!  Naturally, my brandy-new NTE book *doesn't*
> cross these chips.   The charger's called "Smart Charger" [haw!!] and is made
> by Alexander Mfg, Mason City Iowa.
> 
>         MSM5842-19RS      "OKI" in a diamond logo
>         ADC0808CCN        National, I think
> 
> The negative side of the battery pins is fed off three ganged pins of the
> ADC0808.  Anyone know what these chips are?  This whole picture is seriously
> weird....

	I'm impressed...

	This battery charger not only has a microprocessor, but also has an
A/D converter to measure charging current and/or voltage.  The OKI chip is
a microprocessor with 768 bytes of ROM, 32 nibbles of RAM and about a dozen
I/O pins.  It runs at a maximum of 4 MHz.  The National chip is an 8-bit A/D
converter with internal 8-channel multiplexer.

	Sounds like someone has designed a battery charger circuit to do
things the right way.

<>  Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp.
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