Power to the People

A big percentage of the questions I get about the Betalert 10B deal with the power supply section.  Below is my attempt to recreate the schematic of the power supply section. 

This may not be 100% accurate.  It is my attempt to reverse-engineer the power supply based on some old notes I have laying around.  I drew it using OpenOffice.org’s “Draw” program and I was learning it as I went, so please forgive any clunkiness in the drafting.

Some History

I originally designed the power supply to be a switching supply because they are much more efficient than linear supplies, and thus run a lot cooler.  However, the sales and marketing people balked at the cost, so I was instructed to essentially copy the power supply of the first generation Betalert 10 … and so I did.  I was also instructed to, whenever possible, use parts that we already used on other things.  This saved money by (1) saving the cost of taking out new part numbers, (2) not having to stock additional parts, and (3) increasing the volume of certain parts and thus driving down their unit cost.

Anyway, as you can see, it is a pretty straightforward two-output supply based on a dual-secondary transformer and two linear power regulators.  These regulators were about as cheap as any component could possibly be.  However, they were notoriously inefficient and can get quite hot (hence the heat sink).  Right around the time I was designing the Betalert 10B, Linear Technology was coming out with a line of simple switching regulators that I wanted to use.  However, they were about five times the cost of the linear regulators.  They also had the curse of being “new fangled” and so weren’t given a warm welcome by an industry as staid and as slow-changing as the power generation industry.  So, I was told to ditch the switching regulators and go with the linear regulator supply.

Transient Voltage Suppression

C27 and C28 are high-voltage capacitors used transient voltage suppression.  Note their very high voltage rating of 6000 volts and relatively low capacitance (4700pF).  This should allow them to capture relatively fast high-voltage transients.  Note that these may degrade over time if they take a lot of transient spikes.  They’re a prime candidate for replacement if you are refurbishing an old unit (and let’s face it, ALL of the units are old now!).  The second line of defense for high-voltage, high-frequency transients is the transformer.

Transformer

The transformer, T1, is a split-primary, dual-secondary transformer.  I don’t have any information on this.  I think it was custom designed for the Betalert 10 (not 10B!) and since it was a part we were already using in large quantities on the BL10, I decided to use it on the BL10B.  I can’t remember what the secondary output voltages are.  I’ll get around to measuring them one of these days.  I suspect the pin 6-7 tap is around 5 or 6 VAC and the pin 8-10 secondary is about 20-ish VAC.

Note the presence of the three jumper positions on the primary of the transformer.  These allow the unit to be jumpered for use with either 117VAC or a 220VAC input voltage.  For 117VAC operation, install jumpers A and B.  For 220VAC operation, remove jumpers A and B and install Jumper C.

NOTE:  The factory default was for 117VAC operation, and so jumpers A and B are permanently “installed” using PWB etch.  If you wish to convert a unit to operate at 220VAC, you will need to cut the etches on jumpers A and B and then install Jumper C.

Bridge Rectifiers

Bridge rectifiers CR29 and CR30 are DB-103 type rectifiers that come in a 4-pin DIP package and are rated at 200PRV and 1 Amp.  I was shocked to find that you can still buy these at places like Mouser and Digikey.

http://www.mouser.com/search/refine.aspx?N=4294966144&Keyword=DB-103

http://parts.digikey.com/1/parts/432297-rectifier-bridge-gp-200v-1a-db-1-db103.html

I can’t remember who I had specified as the original manufacturer of these parts, but since the part seems to be something of an industry standard, nearly any reputable manufacturer’s part should work as long as the ratings are equal to or better than 200PRV and 1 Amp.  Verify that the pinout is the same, too!  It will be very bad if they’re not.

5V Regulator

The 5V regulator is a standard 3-pin 7805 type regulator in a DO-220 package.  This is very common part and can be gotten at places like Digikey and Mouser.  Just do a search on “MC7805CT” and any number of them should pop up.  The one I designed in was made by Motorola, but they got out of the semiconductor business several decades ago.  However, any 7805 regulator from a reputable company should work just fine.

The 5V regulator has to dissipate a lot of heat, so if you replace it, make sure you re-install the heat sink.  Apply thermal compound to two places:

1.      Between the regulator tab (ground) and the heatsink

2.      Between the heat sink and the PWB ground pad

After soldering in the regulator and applying the thermal compound, line up the screw holes in the regulator, the heatsink, and the PWB.  Install using a #4 screw, lockwasher, and nut.  (Note:  You can use an even bigger heatsink if you want.  Use any standard DO-220 heatsink.  Just make sure it doesn’t physically touch any other components, the metal case of the unit, or any non-ground PWB etches.)

The input to the 5V regulator is filtered with C25, which is a 3300uF, 35V aluminum electrolytic capacitor.  Aluminum electrolytics tend to become electrically “leaky” as they age, so they are always a good candidate for replacement when refurbishing old electrical equipment.  If you replace it, though, make sure you use a capacitor with a 3300uF (or higher) capacitance rating and a 35V (or higher) voltage rating.  If replacing this capacitor with a physically bigger device, make sure that it doesn’t touch any nearby components.

If I was designing this supply again today, I would also add a 0.1uF, 10V ceramic capacitor between pins 2 (ground) and 3 (output) of the regulator as close as possible to the two pins.

NOTE:  It has recently come to my attention that the 5V regulator section was redesigned after I left the employ of  Hathaway/Beta.  The 7805 regulator was replaced with a LM2925T.  As best I can tell, this is a 5V regulator (similar to the 7805), but with a RESET_N output that can be used to put an external device, such as a microprocessor, in reset when the output voltage is out of tolerance.  I presume the reset pulse width can be programmed through the use of external components.  At any rate, I don’t have any information on either the updated BL10B schematic or the LM 2925T itself, so you’re on your own if you need to service this.  If I get more information, I will post it.  Or, if you have any information about it, feel free to email it to me.

24V Regulator

The 24V regulator is a standard 3-pin 7824 type regulator in a DO-220 package.  This is very common part and can be gotten at places like Digikey and Mouser.  Just do a search on “MC7824CT” and any number of them should pop up.  The one I designed in was made by Motorola, but they got out of the semiconductor business several decades ago.  However, any 7824 regulator from a reputable company should work just fine.

The 24V regulator doesn’t have to dissipate as much heat as the 5V regulator, so a heatsink isn’t strictly necessary.  However, if you replace it or are refurbishing a unit, it is a good idea to reapply some thermal compound between the regulators ground tab and the PWB.  When done, line up the screw holes in the regulator and the PWB.  Install using a #4 screw, lockwasher, and nut.

The input to the 24V regulator is filtered with C26, which is a 100uF, 50V aluminum electrolytic capacitor.  Aluminum electrolytics tend to become electrically “leaky” as they age, so they are always a good candidate for replacement when refurbishing old electrical equipment.  If you replace it, though, make sure you use a capacitor with a 100uF (or higher) capacitance rating and a 50V (or higher) voltage rating.  If replacing this capacitor with a physically bigger device, make sure that it doesn’t touch any nearby components.

If I was designing this supply again today, I would also add a 0.1uF, 10V ceramic capacitor between pins 2 (ground) and 3 (output) of the regulator as close as possible to the two pins.

Sales Catalog Page for Betalert 10 (NOT 10B!)

As I promised in my last blog entry on February 19, here is a copy of the page from the 1985 Beta Products sales catalog that shows the Betalert 10 (the predecessor of the Betalert 10B).

NOTE:  I am not the copyright holder of the sales catalog or of the image presented below.  It was originally published by Beta Products in the 1985 timeframe.  When Beta Products was bought by Hathaway Process Instrumentation a year or two later, the copyright transferred to them.  I'm not sure who bought Hathaway, but I'm reasonably certain that the copyrights have expired.

When I was given the charter to redesign the BL10 to make it less expensive to build, I quickly found out that there was not a lot of material cost that could be removed.  So, I concentrated my efforts on reducing the labor content.  But, being an enthusiastic young engineer, I didn’t want to just make it cheaper … I wanted to make it better.  So I set out to add some features to it wherever I could while still making it cheaper.

Below is a list of differences between the BL10 and the BL10B.

STANDARD SEQUENCES:  The BL10 only provided two ISA sequences (AFL and SFFL).  However, the BL10B provided 7 different ISA sequences (plus a “secret” eighth sequence which was never mentioned in any of the BL10B literature).  The eighth sequence was a three-color version of the AFM sequence, using tri-color LEDs.  However, tri-color LEDs were expensive and so I was ordered to remove the tri-color LEDs from the BOM and replace them with cheaper mono-color (red) LEDs.  Fortunately, both LEDs fit the same footprint, so the unit could be populated with either and would work just fine without any software changes.  I was always really disappointed that the tri-color option was never marketed.

TERMINAL BLOCK CONNECTIONS:  The BL10 used black, barrier-type terminal blocks that were so commonplace in the power generation industry.  However, the BL10B used green Phoenix-type pluggable terminal strips.  I caught A LOT of grief about that from sales and marketing back when I was designing the BL10B.  Phoenix connectors were new to the USA back then and marketing was certain that customers would not like them since everyone in the industry (said marketing) was accustomed to barrier type terminal blocks and would not cotton to these new-fangled terminals that were that ugly green color.  But I stood my ground and I insisted (rightly) that I could not get enough terminals on the back panel if I used the barrier blocks.  The Phoenix connectors allowed me a higher density of connections.

I eventually won the argument (it was about the ONLY argument I won) and we went with the Phoenix connectors.  It turned out that customers loved them and within a year or two, nearly all of our new annunciator products had Phoenix connectors on them.

The big savings here was in labor.  For the BL10, look at the picture of the BL10 in the picture above.  See that big honkin' wire harness sticking off of the PWB?  Each of the wires in that bundle had to be hand soldered onto the PWB.  They also had to have a connector pin crimped onto the other end.  And that pin had to be pushed into the nylon connector shell.  Then, on the rear panel, more wires had to be soldered to the barrier terminal strips, connector pins crimped on the opposite ends, and then pushed into the mating connector shell.  That was a lot of labor!  And, in talking to the ladies who actually built these things, they said it was nearly impossible to get those two nylon connectors pushed together when putting the units together.  It was hard for them to get their hands into the units to push them together.

Now compare that to the BL10B.  On the BL10B, the Phoenix connectors were wave-soldered directly onto the PWB during assembly and, when the assembled PWB was slid into the chassis, the Phoenix connectors stuck out through cut-outs in the rear panel.  There was no soldering of wires, crimping, or mating of connectors at all!  It was labor-free.  I was really proud of that change.

MICROPROCESSOR:  The processor on the BL10B was a Hitachi HD63A03, whereas the BL10 used, I think, a Motorola 6800 or some derivative of it.  The source code for the BL10 had long since been lost by the time I began work on the BL10B.  I believe it was somewhere in the back of the building on an 8-inch floppy disk (for which we had no disk drives).  The HD63A03 was actually a Motorola MC6303 that Motorola granted a license to Hitachi to manufacture using CMOS technology.  This meant that it drew less power.  It was also one of the very earliest examples of a “system on a chip” microprocessor.  It had a built-in UART, digital I/O, and some programmable timers and counters.  It was a pretty cool device in its day.  It’s pretty primitive nowadays, though.  Ahh, how I miss programming in assembly language!

LED DRIVERS:  The BL10 used discrete transistors to drive the LED and relays.  The BL10B used IC-type drivers that were an 8-bit wide logic latch that drove 8 open-collector output drivers.  I think I did that to save PWB real estate . . . or something.  I can’t remember.  It seemed like a good idea at the time, though in retrospect a 74HCT373 and 8 transistors probably would have been cheaper.  But I was young . . .   Or perhaps I just didn’t relish the idea of laying out 16 or so discrete transistors and their associated discrete components on a PWB using black tape on mylar.  I’d probably STLL be laying out that PWB!

PROGRAMMABLE FEATURES:  The BL10 used gold-plated Cambion jumpers to select various programmable features.  The BL10B used DIP switches.  I think I went that route for PWB real estate reasons.  Plus everyone in the factory that did final assembly or test hated Cambion jumpers.  You needed needlenose pliers to install or remove them and more often than not they would pop out of the pliers and go flying.  They looked like golden staples  … and were just as sharp.

LED INSTALLATION:  The BL10 had LEDs that were mounted to the front panel and were then connected to the main PWB via discrete wires.  For the BL10B, Tom (our draftsman, but essentially a mechanical engineer), and I found a way to ingeniously install the LEDs on the back side and on the edge of the PWB such that they protruded at just the right spot in the front panel.  That saved assembly cost (i.e. labor).  Unfortunately, it required us to drill a cutout for the LEDs on one end of the engraved legend plates in order to make it work.  But no one ever complained about these non-standard legend plates.

 ======================================================

That’s about all I can remember, though I’m sure there were other differences.

A Trip Down Memory Lane

While cleaning up my home office a few months ago, I came across an old sales catalog from Beta Products.  Per a notice on the back page, it was copyrighted in 1985.  This was actually a year or so before the Betalert 10B came out, so there is no mention of the Betalert 10B in it (obviously).  There was a page for the Betalert 10 (the predecessor of the Betalert 10B).  See the next blog entry for that.

Finding this catalog was definitely a trip down memory lane for me since it has some pictures in it of the factory at the time, so I thought I’d share some snippets of it with you.

NOTE:  I am not the copyright holder of the sales catalog or any of the images presented below.  They were originally published by Beta Products in the 1985 timeframe.  When Beta Products was bought by Hathaway Process Instrumentation a year or two later, the copyright transferred to them.  I'm not sure who bought Hathaway, but I'm reasonably certain that the copyrights have expired.

THE BUILDING

Above is a picture of the Beta Products building in Carrollton, Texas as it was in 1985.  I loved that building.  It was humongous (at least to me).  It was a relatively new building then and was clean and neat and well lit.  It was heaven to me. 

The front quarter of the building was split into two floors and was the office area.  This consisted of engineering, drafting, document control, sales, marketing, accounting, personnel (it wasn’t called HR back then), production control, etc.  The back three quarters of the building was “open” (i.e. a single floor that was two stories tall) which contained inventory, printed circuit board assembly, product assembly, product testing, quality assurance, systems staging, packing, and shipping.

We only remained in that building for about 2 years after I joined the company.  Around that time we were bought by Hathaway Process Instrumentation and it was decided we would move a mile or so away to a cheaper facility.  The former owner of Beta Products also owned the building above and, after the sale, water-cooler rumor had it that he was asking an outrageous monthly lease figure.  So we moved.

The building in the picture above is still there, but it was bought by a church not long after we moved out and is still a church today.  I’ll try to drive over there and get a picture of it someday and post it.

The Reception Area

This was our lobby area.  The receptionist was named Chris and was the sweetest and classiest lady you could ever hope to meet.  As the first impression people had of Beta Products, she definitely put a great face and a wonderful voice to the company.  They don’t make ‘em like her anymore!

That chair there to the right is where I sat when I walked in off the street (literally) to apply for a job after college.  I didn’t have a car (or much of anything, really).  I just “cold called” in there for a job one day.  Chris told me years later that she and a few of the other ladies that worked there had watched me walk out the door after my interview and begin walking down Beltline Road (a relatively desolate highway back then).  I walked the two miles (approximately) to nearby Coppell where I was staying with an old college buddy of mine until I could find a job.

I can’t remember if that palm tree next to the chair was real or fake.

Sales and Marketing

This was our sales and marketing area.  It was located directly above the lobby in the previous picture.  Being a lowly engineer, I didn’t get to go up there very often.  The one person in the picture whose name I remember is the woman sitting at the word processor.  (I only remember her because I had a crush on her for the longest time, though she was probably ten years older than I was).  She was extremely sweet and personable.  I thought she was the bee’s knees.  Unfortunately for me, she was happily married.

In the foreground, get a load of that gigantic IBM Selectric typewriter!  It was a beast.  I think it was one of the ones with the extra wide carriages in it for funky-sized legal documents and whatnot.

Notice, too, the PC-looking thing that she is staring into.  That wasn’t a PC.  It was a dedicated word processor.  It ran “Symphony”.  I had to use it once for something and it was very clunky and unintuitive.  She would usually step in and rescue us poor engineering lunks and offer to do the typing for us.  She knew the system inside and out and could type like blue blazes.

Other equipment from the period:  the Rolodex, the Telex, green-bar paper.

Assembly Line

Here is a shot out on the assembly line.  Most of what went on here was wiring up the chassis for various products.  The annunciators we built back then contained a LOT of wiring.  The lamps that illuminated the annunciator windows fit into sockets, which were connected with discrete wires to card-edge connectors into which the logic cards were plugged.  The logic cards contained the circuits that performed the various ISA flash sequences.  Also hand-wired were the auxiliary relays, power, pushbuttons, etc.  So, for a typical 48-window annunciator with two light bulbs in each window, this amounted to a LOT of wiring.  Those racks and shelves against the wall to the right in the picture were basically nothing but spools of wire of different gauges and colors and insulation materials.  You can also see the “crimping” machines, that automatically stripped an eighth inch or so of insulation off of the wire and then crimped connector pins onto them.

Away far in the back of the picture, though it’s hard to see, was the mechanical assembly area.  This was manned by a lone, elderly man (I forgot his name, sadly) who put together all of the chassis for all of our products.  Sheet metal parts (sides, tops, fronts, backs, brackets, etc.) would come out of our sheet metal shop and he would screw, bolt, and rivet them all together to make the annuciator “box”.  It would then make its way up to the tables where it was wired.

I have forgotten nearly all of these ladies’ names.  The main one I remember is on the front table at the far right of the picture.  She and I actually became very close friends, though I lost contact with her about 15 years ago.  She worked her way up from the line, to running the stock room, to eventually becoming the purchaser.  We were quite the daring duo by the time she was purchaser.  By then I was the engineering manager (much more impressive-sounding than it actually was) and when vendors would invite her to free lunches or give her free tickets to go see the Texas Rangers or something, she'd invite me along with them.  Those were the boom-town days in electrical gadgetry.  Parts vendors were constantly providing all sorts of nice freebies (dinners, lunches, game tickets, etc.)  Good times.

(By the way, the two white circles in the photo above are from the holes in the sales catalog for three-ring binders.)

Wave solder machine

This was our wave solder machine.  All of our printed wiring boards were for through-hole parts back then, since surface mount technology was still in its infancy and generally only used in high volume products.   We had a half-dozen or so ladies who stuffed parts into PWBs all day long.  When they had a big enough batch of them, they would be taken over to the wave solder machine and ran over a sort of “waterfall” of molten solder.  This would solder all the parts to the board.  They then went to QA and then on to test.  The lady above, at the time I worked there, was the person that had been with the company the longest; something like 30 years or so.  She retired at some point while I was there, towards the end of my tenure.  She was really nice.

Metal Shop

This was our metal shop.  Most everything we built was made out of sheet aluminum.  For most products, exposed but generally unseen aluminum surfaces (e.g. the backs of units) were brushed aluminum.  The front panels were unfinished (i.e. smooth) aluminum or steel and were painted black.  We had all kinds of equipment:  NC punches, bending equipment, shearing equipment, etc.  It was pretty cool to watch.  I can’t remember the gentleman’s name shown in the picture above, but he was a very good machinist (or whatever they were called).

Packing and Shipping

When a product or system had passed test and went through QA for sell-off, it went to the packaging and shipping department.  This was a one-man operation for the most part.  I can’t remember the gentleman’s name above, but he was a very nice, very decent man.  His daughter worked in various positions in the company over time (engraving, document control).  The main thing I remember about the man above is that he absolutely loved Old Spice aftershave and so you could always tell where he had been throughout the building.  But for him, it worked.  It wasn't obnoxious.

There was some cool equipment in the packing department.  There was this machine that was loaded with a large spool of paper packing tape (you can kind of see it in the picture between the man’s desk and the loop of hoses).  The tape was made out of brown paper and was about four inches wide.  It had some sort of threads (nylon maybe?) that ran the length of the spool and were embedded into a sort of non-sticky adhesive, about four or five threads spaced equally across the width of the tape.  On the machine you could punch a length (say, 36 inches) and it would feed that length of the tape across a reservoir of water, activating the adhesive on the backside.  That tape came out plenty fast, so you could get a really nasty paper cut on it if you weren't careful.  It would then cut it off to the desired length.  You then took the tape and used it to seal the boxes.You can see some in the picture above, forming a cross on the tops of the boxes in the foreground.

Another cool device was the spray foam machine.  You can see the hoses for it off to the right in the photo.  Once you got the product wrapped in plastic and set into the shipping box, you would spray liquid foam into the box and it would expand to fill the box.  It was really cool to watch!  This was the precursor to the foam insulation we use in houses nowadays.  I remember the foam in liquid form was super hot.  If you got any on your skin it would burn the bejeebers out of you.  And if you got any of the liquid foam on your clothes, you pretty much had to throw them away, because it would become an integral part of the weave of the cloth.  (Don’t ask me how I know these things … lol!)

Also, as you can tell from the photo, it was about ten minutes to ten o’clock.  Or possible ten to 4:00.  It’s hard to tell in that grainy picture.

======================================================================

Anyway, that was my trip down memory lane.  Those were wonderful years at Beta Products and I really miss them and I miss all of the people.  For that very brief moment in time, we were a family.

Betalerts In the Attic

While rummaging around in the attic this past weekend looking for a Betalert 10B user's manual, I stumbled (almost literally) across an old Betalert unit that I had forgotten I had. I was pretty sure I had my original prototype up there somewhere, but this unit I found was not that unit. My prototype is easily identifiable because the front panel is completely unpainted. It is just brushed aluminum with no LED legend plates on it. But, as you can see from the picture below, the unit I found looks like a real unit.

After thinking about it for a few minutes, I began to have vague recollections that this was a demo unit that had been put together for one of our salesmen to take out the road with him. Note that the legend plates are not screwed on, but are merely glued on. I can't remember why the unit was put together that way. I guess he needed it in a hurry and couldn't wait long enough for someone to go find the screws for him. Anyway, at some point he got a production unit and no longer needed this unit and was going to toss it. Fortunately, I found out about it and appropriated it.

I can't remember if it works or not, but I guess it doesn't really matter. I saved it from the dumpster mainly for looks and not because I needed a functional 10-point LED annunciator.

As you can see from the sticker below, it is serial number 52107. Color me skeptical. This unit was more likely among the first ten or twenty units we produced. But I think they picked the starting serial number to be something higher than the last serial number for the Betalert 10A, which was being phased out. So, on second thought, I guess such a high serial number is not too outlandish.

There is a date stamp on the bottom of the printed circuit board that indicates the unit was built around July 29, 1987.

The printed wiring board (PWB) has a revision of A, so this is my second pass at the design. I'm not sure what I fixed, but I know that this was not the final revision of PWB because the oscillator footprint had not been fixed yet. When I originally laid out the PWB, I somehow managed to get the holes for the oscillator leads just a hair too close together. Believe it or not, that was about the only mistake I made on the PWB. Considering that this was back in the days when PWBs were laid out using black tape on clear Mylar, that wasn't too bad!

Original Betalert 10B Advertising Flier

Here is a scan of the original one-page Betalert 10B advertising flier.   (Or is it "flyer"?)

This is the sort of thing that would have been handed out at trade shows, put into distributor's or representative's sales binders, or mailed out to prospective buyers.  I was proud as a peacock when these were first printed and showed up at work.  I "appropriated" a dozen or so as souvenirs.  But now I'm down to one of these after one of my attic-cleaning binges a few years ago.  But one is all anyone would need, right?

Click on the images for a larger view.

NOTE:  I am not the copyright holder of the two images above.  They were originally published by Beta Products in the 1986 timeframe.  When Beta Products was bought by Hathaway Process Instrumentation a year or two later, the copyright transferred to them.  I'm not sure who bought Hathaway, but I'm reasonably certain that the copyrights have expired.

Introduction to this Blog

I am the designer of the Betalert 10B, which I designed more than 20 years ago.  This blog is a labor of love for me and I hope it serves as a combination user’s group, fan club, and historical record.

But I am realistic.  I don’t expect that this blog will suddenly create a huge demand for Betalert 10B units.  I don’t expect people will suddenly start using them.  Heck, I’m not even sure any of them exist any more!  But the Betalert 10B was my first real design, the first one I did completely on my own, and I feel a sense of paternity towards it.  Just like a father might go looking for a child he hasn’t seen in 20 years, I am looking for Betalert 10B units. 

Please feel free to email me of any information at all that you have concerning Betalert 10B units.  You can tell me that you saw one operating at a coal-fired power plant in Minnesota.  You can tell me that you saw one at a garage sale in Nebraska.  You can tell me that you saw one being used as a wheel chock on a 747 in an aviation graveyard in the desert.  I don’t care.  I just want to hear stories about whatever became of my baby.

You can email me at:  BL10B@yahoo.com

In the blog entries to come, I hope to give provide:

• A brief history of how the Betalert 10B came to be
• Whatever technical information I can get my hands on (schematics, firmware snippits, etc.)
• Sales literature
• Whatever else I can think of to say about them.

DISCLAIMER

(I hate disclaimers, but in this overly litigious age we live in, I feel I must protect myself.  My apologies up front.) 

I assume no legal, financial, or any other responsibility for anything concerning the Betalert 10B or any information about it that I present here.  I designed it while in the employ of Beta Products and I retained no rights or obligations to the design or the units themselves.  This is simply a labor of love for me.