HP-41 Speed Upgrade

[knife31]

Back in the early 80's a friend and I added a resister internally (not sure what we added as he was the smart one) to the calculator that was activated by a magnet on the side of the HP. Does anyone remember where the instructions for this upgrade are?
Randy

[MeindertKuipers]

Back in the good old time I was such a friend and did various upgrades, speed and module doubling, or building a module inside the HP41. It was a capacitor that was added, and a magnetic reed switch to switch back to the original speed (for card reader operations mainly).
The instructions are somewhere in the (archived) PPC Journals, so you need to look at the indexes.
Today I would not attempt this anymore and I only take an HP41 apart if I really need to do that because of the fragile screw posts. Simply too much risk. If you want a fast HP41 better invest in a DM41X or HP41CL.

[Hiwi]

Hi,
it was published in the CCD "Prisma" as well.
But it should not be a great thing with a T-Flipflop (74HC74 or CD4013...) and a reed contact. to switch a coil or capacitor in the LC oscillator.

There were mods switching into Turbomode with key combinations. Many other people installed a small switch from Secme France to toggle the speed, this was done so in the HP41CY Turbo.

W&W has it on the left side, it should be possible in the battery compartment.

It was a big hype in the 80er to speed up every machine, HP75,HP71,HP11,HP15 and so on.

And the little switch was the holy shit, very hard to get :-) Only some "gurus" deigned to give it away to the "mob". :-)

As far as i know there were only issues with the cardreader in Turbomode. And the Beep / Tone signals were higher. But this was used to test whether your are in TurboMode.

If you don't use a cardreader you can make a permanent modification

And not every HP41 runs at 2.3 times speed. You have to try out. My early HP41CV only runs at 1.8 times speed reliable.

Happy programming.
Ralf

[knife31]

I'm guessing you're German. My friend was Jurgen Schleucher, we were both in Hanau at the time, 1980-1984.

The HP-41 I'm talking about, has had the modification and seems to be on the fritz (Off/On problem). Bought another on E-Bay.

I was thinking about turning it into a HP-41CL and wondered if the mod would screw it up or the off/on problem was something worse and I couldn't convert it.

You are correct in that you had to remove the magnet before you use the Card Reader, at least in mine.

Randy

[knife31]

Found it in PPC Journal V6N1P32. Looked in Prisma, and somewhere they have an index I'll let you know

[Hans Brueggemann]

PRISMA 84.2.33

[Sylvain Cote]

(03-05-2024 04:49 PM)knife31 Wrote:  Found it in PPC Journal V6N1P32.

This article is for the HP-67, the first speedup article for the HP-41 appeared in PPC Calculator Journal V8N5P3 July 1981.

[knife31]

Thanks

[Etienne Victoria]

And later in april 1982 in France :

in L'Ordinateur Individuel

E.