Yeah !!!
55 wired up, oscillates !
Put a couple 100K resistor and 1uF cap as an easy starting point with round numbers. Ran the math, gave a theoritical frequency of 5Hz, just the ball park I need so impeccable.
Works perfectly. ON time is spot on the OFF time as it ought to be, and frequency spot on 5Hz. I am in heaven, it's a good start !
I calculated that a Frequency of about 20Hz (18.2Hz), would be good. Divided by 2^16 (x2 8 bit counter TTL chips cascaded), it would give me a one hour period.
So let's now fine tune this to get about 20Hz and add a pot to vary the duty cycle
No RPN! But TI-85. Acceptable
Actually really nice calculators and not the same heritage as the TI-83 as you can tell because the people who designed this didn't make the exponent key shifted. The screen was shit but they fixed that in the TI-86, which I had one of
Ti 83 ? 86 ?! Don't know these...Hell I thought you were older than me not younger !
I was born in 1977, and AFAIR when I was at school the TI range was the TI 81, 82 and 85.
81 was a bit bottom of the barrel to my liking back then... well no honestly I just hated the colour. Much preferred the gray of the 82, so I convinced my mum to fork out 750 Francs for it. Was a huge sum for her, so I was very thankful. Well I think our applied physics teacher did also recommend the 82, to boot.
I loved it, it's well suited / tailored to engineering I find. The 85 was so expensive that only one guy in my class had it. But I didn't like it because it was more suited to pure science and math... the K/B layout was not as practical for engineering I found. some basic functions were not as easy to access I found. Still, I was jealous of his 85... so 25 years later, recently, since they are now dirt cheap, I got one, got my revenge !
About 5 years ago. When I received it, I had a "surprise"... inside the slide cover, there was something written on it in big letters, by hand with I don't know, nail varnish or something similar, but silver looking. Like the conductive varnish to repair heated rear screens on cars.... anyway it read : " BASTARD !!! ". Yes in French it means the same as it does in English !
The seller omitted to inform of this...
So I scrapped the varnish as best I could, but still !
Anyway as I said the 85 is a pain for basic engineering tasks I find, so I would much prefer using my own 82 of back in the day. Problem is that the LCD is kaput, vertical lines all over it
I guess I could try to heat the cable see if that fixes it....
Anyway. Back at school, circa 1995 or 1996, other than that ONE class mate with a 85, there were two other mates that had a one-off as well. One had a Ti 92 ! A monster calculator, more of a portable computer than a calculator. huge screen, mega large K/B, needs to hands to operate it, a monster. Runs on a 68K CPU with 128K of RAM. Way too big and heavy in the bag to be practical, but boy in awe all we were, blown away by this thing !!!!
Then another guy had an HP 48 ! I remember I found it very "expensive". I mean the quality of the material and that of the build./construction, looked much better than the Ti. Also had a lovely comfy velvety pouch to keep it warm !
ISTR I found the quality of LCD better than the Ti. Had a cool Infra red link rather than a wired/cable for the Ti, however since the HP was so expensive he was the only one with a HP so had other calculator to connect to !
I do seem to remember however, that I didn't like the K/B at all ! It was 25 years ago so am not 100% sure, but I think I found the keys hard to press and noisy, compared to my Ti 82. Made typing both uncomfortable and slow. Again, old memories so could be off...
So yeah, at school it was either 82 for most of us, and 85 / HP 48 or Ti 92 for the more wealthy of us.