WP34S: Reset when printing statistical registers?

[jebem]

(07-03-2014 10:39 AM)rkf Wrote:  

(07-03-2014 10:30 AM)Paul Dale Wrote:  ... Most likely, we're drawing too much current from the coin cells and their voltage is dropping because of this. I've seen this too from time to time and sometimes the low battery indicator comes on briefly. ...

What a pity, just set ()DLAY to 0 again to provoke the Reset message, and watched closely the LCD panel while doing a print summation registers, trying to glimpse the Low Batt annunciator. Unfortunately, this time neither a Reset shows up, nor a broken I/O character is printed - no matter how often I try.

?!?

Kind regards, Ralf.

Interesting subject. A couple of questions...
- Did you get your WP-34S ready made, or did you install the IR LED yourself?
- How far can the calculator be from the printer and still get a good connection?

IMHO the IR LED current should not be too high when compared with what the calculator processor can consume.
I would say that the HP-30B can consume as much as 20mA in many situations, and the IR LED should only add a few mA more, maybe 2 to 4mA in a proper implementation and using one adequate and efficient IR LED type (however with that current values I would expect the working distance range to be small, like 30cm or about 1 foot at maximum).

But the real IR LED current consumption can be higher, depending on the circuit used to drive it. If the IR LED series current limiter is absent or is of a very low value (below 330 ohm), it can deplete the batteries in shorter time than normal, but you should be able to communicate at larger distances in this case!

From your description, the probable cause seems to be a voltage drop condition from the batteries you are using.
Sometimes the batteries recovers by themselves, yes, but in the end it will happen again soon.
And not all the battery brands are created equal...

I would try a new set of battery cells and see.
I get my batteries from China in the TAS for peanuts and the quality is more than acceptable for the asking price and free delivery.

As a final note, if you enjoy a little diy and have a multimeter, you may use an external 3Volt power supply (two AA batteries in series will do), a couple of cable clips to connect it to your calculator and measure the current consumption when printing to find out more about your calculator current consumption.