DIY calculator: HP30b to WP34S!

Posted: 12/30/2013 11:37:49 PM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

"Wow!"

LOL, its not quite as grand as it sounds ;-)

I was working for a company making motors/controllers etc and joysticks (wheel chair parts) who ventured into electric vehicles when bought by a new Welsh proprietor - And the new owner knew Sir Clive, who was at that time also looking at a new EV..

A couple of meetings occurred - but it never went anywhere.. My boss went on his own EV venture (Converting a Mini into an EV) to showcase his in-wheel motor - the final outcome was the company going to the wall... 

 

Posted: 12/31/2013 12:51:50 AM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"...his in-wheel motor - the final outcome was the company going to the wall..." - FredM

Was it a "sprung vs unsprung weight" thing?  Or bad just business timing?  Or the lack of decent batteries? 

Honestly, most of us could probably get by with glorified golf carts, particularly if we didn't have to share the road with 18 wheelers.

Posted: 12/31/2013 1:10:39 AM
Jeff S

From: N.E. Ohio

Joined: 2/14/2005

"Honestly, most of us could probably get by with glorified golf carts,..." - dewster

Hey...I think my Dad had one of those back in the '70's.  It was an Opel.  You could "floor it" (AKA "pedal to the metal"), and it would go, "putt....putt....putt...putt...putt..putt..putt..puttputtputtputtputtputtputt...".  LOL

Posted: 2/19/2014 5:55:24 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Was poking around adafruit.com and ran across this fascinating item:

http://zeptobars.ru/en/read/FTDI-FT232RL-real-vs-fake-supereal

From the article: "Fake chip was working kinda fine, until FTDI released drivers update, which were able to detect fake chips via USB and send only 0's in this case. It was impossible to foresee any possible further driver checks without full schematic recovery and these hidden tricks saved FTDI profits."

Hmm. Seems like a boneheaded move by FTDI, punishing otherwise innocent customers who thought they bought something from them.

BTW, my serial cable now has an obvious melted area on the plastic, opposite the USB symbol side. It doesn't get hot, or even warm to the touch, but I'm not going to leave it plugged in anymore for fear of a fire.

I took it apart, here are some pix:

It appears to not have the promised (by newegg) FTDI chipset, but the PL2303HX from Prolific.  Sure seems to have gotten hot at some point.  Either that or the housing plastic has a really low melting point.  I'm using it to power my FPGA board, but that's 5V direct from the USB port and only 150mA or so.  There are a few passives on the other side, as well as a 12MHz xtal, but no obvious 3.3V regulator, and no obvious discoloring of the PWB.

Posted: 5/5/2014 7:18:16 PM
ira allen

Joined: 5/5/2014

The fact that I need to ask these questions probably means this project is beyond my abilities, but I'm going to ask anyway.

 

What are you connecting the grounds to in in your picture?  That would be both the black lead from the NewEgg cable, and the center battery conductor?

 

Perhaps related, but do you not need to supply power to the +3V rim connector?

Posted: 5/5/2014 9:17:00 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"What are you connecting the grounds to in in your picture?  That would be both the black lead from the NewEgg cable, and the center battery conductor?"  - ira allen

Yes.

"Perhaps related, but do you not need to supply power to the +3V rim connector?"

The batteries are in parallel, so the remaining battery on the left is supplying power to the calculator.  I think they went with two batteries to increase the peak current available.  One works fine for programming.

Posted: 5/6/2014 1:19:32 AM
ira allen

Joined: 5/5/2014

dewster,

Thank you for answering my questions.  It has been 34 years since my last circuits course so I want to make sure I understand.  The black ground lead from the Newegg cable goes out of the picture and then back into the picture connected to the central battery conductor, with no side side trips to any other device?

Interesting about the battery providing power during programming.  I've been all over the internet and have not seen that stated anywhere else.  Certainly makes things simpler.

I really want one of these and your method seems like the cleanest way (once I'm sure I understand it) to get around the cable problem.

Thank you again, I do appreciate it.

 

 

 

 

 

Posted: 5/6/2014 1:59:16 AM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"The black ground lead from the Newegg cable goes out of the picture and then back into the picture connected to the central battery conductor, with no side side trips to any other device?"

Yup.  I haven't a clue as to why the WP guys aren't more proactive in helping others pump up the HP30b with their SW load.  Took me like forever to figure out / decode their HW interface stuff and it turned out to be stupid simple.  There are people over on the HP fora showing off their mad skilz by doing eBay DIY 2x3 2mm pogo connectors with beryllium copper clips and custom level translators and basically scaring everyone off (as it did me for a couple of months - and I'm an EE!).  They really need to stop talking about the non-existent Atmel programming cable as it just muddies the waters.

Anyway, there's literally nothing to it.  Reset it with a paper clip, pump it with a $4 USB TTL RS232 interface (with some 1k resistors if you're feeling squeamish) and call it a day.  If you think you blew it, try again.  The keyboard stickering (particularly the background grid) is more work IMO.

Posted: 5/6/2014 2:38:20 AM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Here's a fantastic video (sometimes I love engineers):

He snaps it apart with his bare hands (~1:45)!

Posted: 5/6/2014 6:03:38 PM
ira allen

Joined: 5/5/2014

I know what you mean about the postings with people showing off with the connectors, clips, and all that other stuff.  Think I read all of them, including your responses there you basically say to chill out - not necessary.  Definitely correct on the confusing part, at the end I was shaking my head thinking what is it I really need to do.

I just had those two questions which you have kindly answered, so I'm in.  I'm ordering all the parts next.  I'll let you know how it turned out.

 

 

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