Everything Vintage Tech

Unknown Packard Instruments PCB

I need some help.  I have a PCB that I can’t identify and I am hoping someone can shed some information on this.

It is a Packard Instrument PCB from 1971.  It has the numbers 7100398 and 5065082 on the board.  There are 7 RCA DR-2110 Numitron tubes soldered to the fron and each one seems to be driven by an EL-RAD X72-333.  There is also one AMD  IC with the markings 930159x 7317 and a TI M 7523 SN7446AN.

I am guessing that this is part of either a counter or a calculator of some sort.  Specifically, I would like to know what this device is from and what the EL-RAD components did.  I can’t seem to find much information on either one.  If you have any guesses, please leve a comment below!

More photos:


  1. It’s actually a prototype for a flux capacitor type of device. There are two components missing. I could tell you what they are and where to put them to make it work, but then I would have to kill you.

  2. “First, you turn the time circuits on. This readout tell you where you’re going, this one tells you where you are, this one tells you where you were. You input the destination time on this keypad.”

  3. This appears to be an old calculator. The tubes on the wide end of the board are actually part of the display. The EL-RAD components are drivers for the tubes (Which i assume are similar to Nixie Tubes). The El-RAD’s are used to light the appropriate segments of each digit the same way a LED driver is used for 7 segment LED displays. Neat find.

  4. I once had a broken Nixie tube voltage meter of about the same vintage. Since I scavenged it for the tubes, I didn’t get too far into the circuitry, but what I remember was a pretty clever hardware successive approximation circuit. A counter counted up with outputs through a resistor ladder to make a sawtooth (I’m inferring this, it didn’t actually work). A comparator detected when the sawtooth hit the input voltage, and the counter was latched to display that digit, and the input voltage was divided by 10 and the sawtooth subtracted off to get the next significant digit.

    It was considerably more complicated than the board here, but perhaps similar principles with the counter and resistor (ladder?) array?

    (Thanks Windell of EMSL for the link).

  5. This is no calculator – If the front “figures” of the VFD tubes are facing AWAY from the main board, then where would the calculator keys go? they would go over the main board. Even for a desktop, you would not have the display mounted vertically with the mainboard projecting out behind it and the keyboard projecting out in front of it.

    Packard made some serious test gear and this almost certainly will be a part of some test gear. Assuming it was a specialised instrument, then I should say it was most likely part of a counter/timer (ie, frequency meter). The main reasons for using Vacuum Fluorescent Displays were readability in a desktop environment (large figures, easily readable even in strong sunlight/artificial light) and sometimes for their fast response times. Both of these are excelent reasons for using them for counter/times.

    The circuitry seems to be simply for driving the displays. Have you tried looking up the data sheets for confirmation? I’m doing this from memory of many years of electronics consultancy…

  6. Thanks for the replies, everyone. I tend to agree that this was probably not from a calculator. I hadn’t considered the direction that the numitrons were facing, however. After probing it some more, I really think this board doesn’t do anything other than display the digits. No real functionality seems to be built in to it.

    @Golog – they are more like 7 segment LEDs than nixie tubes. It is an incandescent seven display so I think you’re right about the EL RAD components.

    @Jon – I just saw the EMSL link come through the other day. Much appreciated, it generated some good responses. I haven’t been able to find any other related circuitry. I’ve been scouring eBay and surplus shops trying to learn more but haven’t been having much luck. This board appears to be display-only. BTW, I like your sculptures.

    @Calc Man – I have tried finding more information on the individual parts however given their age, I am not turning up many results online. I found some info on the TI components (BCD driver, if I remember correctly..) but not much luck on the EL RAD or AMD ones.

  7. I dont know if this is of any help but Packard Instruments is located in Downers Grove, Illinois.
    (a suburb of Chicago) They make scintillators (a type of nuclear instrument) what you have is definitly one of their boards, Back like 30 years ago I used to dumpster dive at their plant it was a goldmine for exotic electronic components. I remember finding Nixie tube boards in their trash.

  8. That is a binary to decimal converter. Sort of a Generic converter used in digital volt meters and such.

  9. The 7446 is an open-collector 7-segment LED driver, IIRC. It turns BCD into outputs for each of the 7 segments.

    74159 is a 4-to-16 decoder, so perhaps the 930159x 7317 is the digit-select demux?

  10. Specifically, which device I could not say, however it is a Nixie tube driver/display card. Check Google. The form factor is too large for their scientific calculators sold during the early 1970’s . It is more in line with their bench-top frequencies counters, digital volt meters, and other electronic equipment. Most likely coming for the Lovaland Colorado LID group (Loveland Instrument Division). The products were not sold long before the 7-sesment LED hit the market.
    Being an old gray guy, I used this equipment but had no reason to look inside.

  11. i worked for packard (oh good times) and most probsbly it is a board that show the number of radioactive counted particles.
    the grandfather of the actual led screen…

  12. btw: packard instrument… they made beta and gamma counters in downers groove (il).
    today has been acquired from perkinelmer (oh my god)…

  13. Thanks for the info! I was searching for “Packard Counter” before but was not finding anything except HP counters. “Packard Particle Counter” is returning better results. Thanks for the tip!

  14. I was the gamma counter product line manager at Packard Instrument Co, Downers Grove, IL from 1972 to 1981. The confusion between us and the better known Hewlett Packard Co. was the universal problem for us and HP.

    As for Nixie tubes, they were long gone but I saw them on the earliest spectrometers laying around in the Service dept. In their time they were the most up-to-date way for digital display the pulses being collected from beta and gamma scintillation detectors… particularly at high count rates. It is difficult to imagine an HP calculator having the need for fast displays of this type.

Leave a Reply