Motorola HEP semiconductors.

"Hobbyist, Experimenter, Professional"

It was late enough that most of the parts were silicon.

It was a combination of a universal replacement parts line along with some interesting parts like some early single chip audio amps, digital dividers, and the like. Some stuff to fix stuff with, some stuff to play with. A selection similar to the parts section of a Radio Shack (of a couple of years later), targeted at the pegboard section of the then commmon local radio parts store.

Those old ICs (single sourced from Motorola) are long gone, but most of the discrete parts would have NTE equivalents.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

Thanks.

As it happens, as I read my way through the archive of Popular Electronics, I stumbled upon a page announcing the end of HEP parts - this was the first and only time I'd seen the definition in print.

That was only a few hours after posting my question.

Any ideas where to look for data/cross-reference? It might be interesting to revive some of those old projects.

Want to spend some money? For $15 ($10 + $5 shipping):

By the way, there were two numbering systems for transistors in the HEP line. For a conversion chart:

David

Thanks - that could save a bit of confusion should I find a cross reference to mainstream parts.

You could ask.

I'm not prepared to give up my HEP replacement guides, or scan them, but if you happened to ask in the newsgroup what HEP-XXX was, I'd probably be inclined to look it up. There was a time when I did that quite a bit, but the internet has evolved quite a bit since 1994, and there are fewer questions like that, I assume because some of the old databooks have been scanned.

Those old construction articles, people would specify what was available. It was never clear if they actually used the specified parts, or just listed parts that could be had easily. As I've said in the past, there were a relatively small subset of transistors and diodes used in the hobby magazines (and I gather a similar but different subset in the UK magazines), though I was never sure which came first? SOmeone had to pick a specific device at some point, all those 2N706s and later 2N2222s, but once they were used, the hobby stores would carry them, which caused others to specify them.

HEP was like that, a line that often was available in local outlets, but really quite expensive. I remember telling a friend in high school that he could just get a cheap op-amp for that lie detector he was building out of Popular Science (around 1974), and he said "I don't want to make any mistakes", so he paid the premium for the HEP numbered device, since the article didn't say anything about the IC except the HEP part number. I don't know if the author used a cheap op-amp in the original, and then specified the HEP replacement because it would be easier to get, or if he actually bought the HEP device to begin with. In that case, it was a generic op-amp, much easier to be sure than a transistor in the line.

The HEP line was different from the NTE and ECG line that came later. It was a Motorola only line. SO they had some exotic Motorola ICs (some came in very odd packages, so you knew that it really was a Motorola device), but if it wasn't made by Motorola, you'd get some line about "approximate substitution", ie a workalike. That was fine for logic gates and op-amps, but it fell apart with really specific parts. NTE and ECG tried to cover everything, their line was much larger as was their replacement guide. So if nothing else, the ECG and NTE guides were better at telling you what the device was, which is all I ever used the HEP replacement guide for.

The HEP line was relatively small when it started, really aimed more at the hobbyist, then got larger a couple of years later. But it was still for the hobbyist or at least professional prototyper, it wasn't extensive enough for the serviceman when it came to ICs. It also wasn't uncommon to find errors in the guide, clearly not the right replacement for a specific device.

What year wsa the announcement that the line was shutting down? I never saw that, and I was still reading Popular Electronics, though mabye sporadically, when it changed it's name and some of its format before dying about 1984. I was never aware that the HEP line had shutdown, only an assumption that it must have at some point, but never aware of when.

Michael

The NTE cross reference book I have has a page and a half of HEP numbers. With the generic nature of "universal replacement", probably "close enough".

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

This reminded me that I have a 1987 "Semiconductor Reference Guide" from Radio Shack (USA). It lists a few HEP numbers, but just the ones that crossed to then-current Radio Shack parts. From this limited set of data, the HEP part number scheme appears to have been, roughly...

HEPnnn transistors - mostly Si? HEPCnnnn ICs HEPGnnn transistors - Ge? HEPPnnn various: one transistor, one optocoupler HEPRnnn rectifier diodes HEPSnnn transistors - mostly Si? HEPZnnn Zener diodes

I scanned the two pages of cross-reference, plus one page of decoder ring. The first two pages will cross an HEPnnn number to a 276-nnnn Radio Shack catalog number. The third page crosses the 276-nnnn number to a standard part number. PDF at:

I hope this helps!

Matt Roberds

Thanks.

The HEP refers to the RCA line of replacement semiconductors, called Hobby Electronic Product HEP

Large catalog of subs and generics. I have a copy in my Libr. If your list is not too long I could look up a few pt no.s

JS

No, HEP was Motorola. RCA was SK.

That reminds me - an SK reference would also come in handy, those parts turn up fairly often in the Indian magazine; Electronics For You.

I don't think I ever saw an SK guide. They existed, but I just never saw one. They were never used that much, at the moment I'm finding it hard to think of where I'd have seen them. THe HEP did get referenced in magazines.

I have a lot of RCA databooks, I knew someone who worked at RCA in the seventies, but I don't think any of the databooks mention SK.

Michael

They were like the ECG and NTE "phonebooks", but I only saw them at the electronics stores. They probably didn't make as big a deal about selling them as ECG/NTE did.

I've even got a NTE floppy disk with the cross reference database lookup on it, for MS-DOS. Looked at the data to see if the data could be extracted so I could run a reverse sort, but it was encrypted/compressed in some non-trivial way.

Wasn't it part of the TV manufacturing, not the Semiconductor division? I vaguely remember that the SK stuff was under Thomson for a while.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

We used ECG, GE, HEP, NTE, SK and Workman in the shops where I lived and worked in the '70s. The SK cross reference was as thick as the ECG. There were several RCA distributors in our area, so the SK line was easy to get. ECG was the best stocked, and most preferred. GE had the lowest quality, just like the semiconductors they used in their consumer products. Some of the floor sweepings from Poly Paks were better than the GE replacement line.

SK was repair parts, not OEM

Probably. I got my HEP guides for free, circling one of those cards in the hobby magazines. I paid for my ECG or NET guide, they were on display at one of the local parts stores. Not a whole lot, but I suppose if they put a price on it, people will take more care of it. But I didnt' see an ECG or NET guide until later, probably the eighties. I'm not sure when they started, but maybe that too was because the HEP line was very much aimed at hobbyists.

I remember that, I may even have the floppy. It was long enough ago that it was "cutting edge", now it's quaint, why have a local copy when it's on the internet.

I'm pretty sure I never bought an HEP device. But I got the HEP guide about 1974, and I found it fairly useful, look up a device to get the general specs, then go through my drawer of scrap transistors to find one that crossed. At least it gave me a general idea of whether something wsa a UHF device or not. But later when I got an ECG or NTE guide, I realized the HEP transistors substitutes had to be fairly vague, since HEP had relatively few devices.

Maybe. But I remember SK was around earlier. It may have simply been intended for the repair business, not marketted to hobbyists like the HEP line. That would make a big difference, even to the guides being in limited distribution.

Michael

Not anywhere I've looked so far!

We're talking about the ECG/NTE line. I forget the URL, but it was online the last time I checked. It may not be perfect, I found it often wasn't easy to get a match (so I wonder if it is looking for an exact match), but it was there.

HEP closed down before there wsa much of an online, and probably before floppies were cheap enough to put a catalog on one.

Michael

There's a collection of NTE data somewhere on my other PC - a search for ECG got me mostly stuff about heart machines etc.

A search with "ecg replacement guide" shows a few sites indicating they have replacement guide in a pdf, so that might be something to pursue. I'm not sure how handy a pdf is, but it would have the specs for the devices (and the pinouts of the ICs) in a complete place.

Michael