Hoyle Quartz LCD
Projection Clock Model # 7770
Oh, where do I begin? I might as well
admit it at this point...
William: Hello. I'm William and I have a clock fixation.
Others: Hi, William.
. . . .
I've never pictured myself as any sort of a clock collector, and most
clocks really are not that interesting at all. Still, I've come across
a few, and like I said before,
a few of
them are interesting enough that I felt it prudent to grab them. And
then, after finding next to no information on the World Wide Web about
them, I've created pages like this one. Not that you or anyone else
cares, but now you know. And maybe you're here because you have this
very clock and need some information about it? Stay tuned, it's all here.
Here are the clocks I found moldering in my grandparents' basement.
Yes, it really was midnight when I took the picture. You'll also notice
that the clocks are "beating against" one another here, as one has its
colons illuminated while the other is turning them off.
As you can see, the unit on the left has had much more use than the one
on the right, or at least has been subjected to a lot more wear and
tear. However, both are interesting because they are projection clocks,
and can display the time of day on your ceiling at night or when the
room is only dimly lit. As for the
brand, Hoyle Products is still around as a maker of card games (you
will notice that their logo on these clocks and on the products they
sell today is--as of this writing in November 2009--identical) despite
their not having a web site. However, at the time these clocks were
Hoyle was a division of a company known as Brown & Bigelow.
Brown & Bigelow is still
and they do have a web site. They make (or, probably more accurately,
distribute) promotional items. And it would appear that they have made more than a
few projection clocks over time, some of which were branded "Hoyle".
I removed the dead batteries and slapped good ones into both units. The
one on the right tried to run and fell over on its face. The one on the
left was lifeless and there was a huge battery mess inside it.
Both of them, particularly the one on the left, would clearly need
repairs to run
again. I really didn't know if I could
repair them. The first problem that I had to clean up was that of
leakage. People have a bad habit of putting portable items aside for
months (or longer!) at a time with the batteries in place. This is a
big mistake. Batteries
contain fairly nasty chemicals and will leak if
given the chance to do so. Do yourself a favor and remove them before
Once I'd cleaned the battery terminals up, both clocks were a lot
happier and able to run. However, the projection can only run on a
constant basis when the power adapter is plugged in. Without external
power, it can only run intermittently when the snooze bar is pressed.
Both were plugged in to a live outlet, and the
power supplies appeared to be working, but both clocks had burned out
light bulbs and therefore could not project the time. The one on the
left had a hot case corner and a very unhappy (hot)
wall wart power supply. So I'd have to crack the cases to see what was
inside and if I could repair it. Both plugs were loose in the casing
and would barely hold the power adapter's connector when it was pushed
Printed in the corner of the display is the word "JAPAN", and it would
lead you to believe that the clock "movement" itself was sourced from a
Japanese manufacturer while the clock itself was put together in Hong
Kong. That's not entirely true. Both clocks were fully assembled in
Hong Kong, right down to the printboard inside. The clock on the left
in the picture above is driven by an NEC uPD833 "8-channel digital
liquid crystal display timepiece and timer circuit with 4MHz or 32kHz
crystal oscillator operation" as per the rather breathless datasheet
title. You and I would probably call it a digital clock controller IC.
And I suppose it qualifies as being a Japanese
clock "movement" of sorts.
Whatever the case, the NEC uPD833 is capable of numerous functions:
The main display in these Hoyle
capable of displaying 24 hour time, and the projection display should
be able to do so as well. Whoever built these clocks did not
take advantage of this, nor did they make use of everything the NEC
part is capable of. More on that later.
- Standard timekeeping
- Alarm function (a buzzer goes off at a specified time)
- Snooze Timer (four minute delay, also programmable to 15, 30, 60
and 120 minutes)
- Sleep Timer (as might be used to control the radio in a clock
- Control Timer (to turn something on or off at a prescribed time
or over a range of time)
- Dual Time (for "world clock" use where the display of time from
two different time zones might be desired)
- Stopwatch (count up or count down, maximum of 23 minutes 59
- Counter (functionality similar to "stopwatch" mode, only the
"counts" are sequential and not confined to timekeeping
standards--meaning that the unit counts steadily up to or down from a
maximum value of 1440 without being bound by the timekeeping rollover
rules, where a rollover occurs every 60 seconds. Instead, a rollover
will take place every 100 counts at some (possibly programmable?)
interval. The 1440 count limit seems odd, as
the display could produce 2888 as a maximum countup total.)
- 12/24 Hour Time Display
As for the clock on the right, it is driven by a no-name controller IC
and fully assembled in Hong Kong, while it too bears the word "JAPAN"
in the lower corner of the display window. I really suspected that this
IC was nothing more than a low-cost knockoff of the NEC uPD833 part,
but such is not (quite) the case. The behavior of both ICs is similar,
but the second clock has a circuit board with fewer interesting
modification opportunities. The NEC part starts keeping time at 1:00 AM
when batteries are put in while the no-name part starts at 12:00 AM.
Some of the symbols in the displays are different, though both retain
the ability to display 24-hour time if it were possible to enable such
a display. Finally, the alarm tones are different. The NEC uPD833 beeps several times in a row followed by a
period of silence, while the
no-name part beeps constantly when the alarm goes off. NEC goes a little breathless on us again
by describing the alarm tone generated by the uPD833 as being a "fine
Oh, and the no-name/knockoff controller peeps on every hour. Sometimes
it also has a beeping alarm fit when the batteries are first installed.
The NEC IC is much more "well behaved" -- it remains silent on the
arrival of each hour as well as when batteries are installed.
Where most clocks reset their seconds count to zero every time you
advance a minute or hour with the setting buttons, these clocks do not
do so. If you want to synchronize them, insert the topmost battery to
start the clock the moment your time source strikes a new minute and
Both clocks have different internals. The NEC-based unit has a circuit
board with several interesting areas, including a number of what would
appear to be "option selects" that govern the controller's
behavior. Those areas have been bridged with solder that connects two
circuit board pads. There is also a trimpot control that probably
should not be played with unless you enjoy getting your clock back to
the point of being accurate. A few resistors, diodes, dipped capacitors
and the clock oscillator round out the parts present on each board.
Then there is the wiring. These clocks have a lot of point-to-point
wiring consisting of thin wire that is very easy to break or separate
from the soldered points on the circuit board. As the ceiling
projection is handled by a separate display unit, the display wiring is
multiplexed by simply connecting both displays together, in parallel.
This assembly consists of tinned wiring grouped together in an
insulated jacket with space between each conductor. It looks like a
very low grade ribbon cable, because that's basically what it is.
You must have batteries in place to allow these clocks to operate. The power adapter is for constant time
The battery and power wiring is very interesting. There are three wires
coming from the battery compartment. Tracing the circuit reveals two
power planes are present in both clocks. The NEC
datasheet states that a second power plane (VDD) is needed
to set the state of some of the IC's functions. Interestingly, both
clocks will operate satisfactorily when a battery is
present only in the topmost position of the battery holder. I take this
to mean that the absence of the VDD power plane is not a
crtical problem The second
connection is used to provide the VDD power plane.
Both clocks, particularly the one based around the no-name IC, have
more than a passing resemblance to the internals of the Micronta 63-753
clock I talk about elsewhere.
no-name IC based clock also has the text "no (0) jewels - unadjusted"
printed on its circuit board, just as the Micronta clock does. There
are, of course, no jewels to worry about in a digital clock!
Hacking / Modifications
The presence of numerous "option selects" on the NEC-based clock's
circuit board open up some possibilities for circuit modification. In
particular, the presence of a "2" shaped character in the rightmost
numeral position suggests that these clocks can keep 24-hour time,
which might be a nice feature for some applications. It would have been
even nicer if Hoyle had implemented a switch to allow the user to
choose which timekeeping method they wanted.
With the face of the clock laying down and the back cover removed, it's
possible to see four bridged solder connections. Studying the NEC
datasheet shows these as being connected to various "mode select" pins
of the IC. In particular, one of the solder bridges connects the 12/24
hour select to the VSS power plane, forcing
the IC into the 12 hour timekeeping mode. I tried to force the clock
into the 24 hour mode. As I have two of them, setting one to the 24
hour method of timekeeping could come in handy.
This didn't really work, mainly because I didn't feel like going to the
trouble of connecting the VDD power plane to the (assumed) VDD
connection in the battery area. To do so would have required lots of
messing around with very fine wire and the very real possibility of
breaking it. The NEC IC would not behave reliably as a 24-hour clock
when I tried setting it to that mode by breaking the connection and
leaving it "floating". It would attempt to function as a
24-hour clock, but the IC tended to reset itself whenever a time value
requiring the display of a leading "2" in the hours position was
requested. Considering that the 12/24 hour selection pin
was floating, this behavior is not suprising.
If someone wanted to go the trouble, a single-pole, double throw switch
could be added to the clock circuit to select between VSS
and VDD power going to the 12/24 selection pin on the IC.
This should reliably set the 12 or 24 hour timekeeping mode.
For now I've undone the changes and have been using the clock as a
twelve hour unit. I may revisit this in the future, if I feel inclined
to do so.
Sadly, the clock based on the no-name IC does not appear to have any of
these "option select" solder bridges on its circuit board. Without a
datasheet for the IC in use (which is larger and has more pins than the
NEC uPD833) I doubt it would prove very useful to attempt modifications
on this type of clock.
Both of these clocks required repairs.
The first problem had to do with the corrosion caused by leaking dead
batteries. The corrosion had to be cleaned off the terminals, and
careful work with an icepick proved effective in removing it. Many
times, though, the outcome isn't this good as the terminals have been
consumed to the point where there is no more metal left or whatever is
left is so brittle that the terminal breaks while being cleaned. Take the batteries out of stuff before
putting it away, people! This sort of thing is PREVENTABLE.
Both clocks use the rather odd (for this application) miniplug
connector to accept power from an external power supply as opposed to a
barrel plug. Over time, this connector has worked itself loose,
allowing the female portion of the connector (the one inside the clock)
to twist around and around until the wiring broke in one clock and
shorted itself out in the other. This sort of plug is used in audio
equipment more often than it is used in power delivery applications.
Fortunately, the "wall warts" supplied with these clocks appear to be
robust and the one that was shorted did not seem to be permanently
harmed by this. The only noticeable effect of the short was excessive
heat being produced both at the power adapter "wall wart" and where the
wiring was shorted together in the one clock.
The other clock simply failed to project at all as the wires had simply
been ripped free of the connector...well, this and a burned out light
bulb kept it from projecting.
Repairs in both cases consisted of cleaning up (untwisting) the wiring
and resoldering it to the receptacle plug. Although the wire proved to
be very fine, it took solder well and the repair appears to be robust
as compared to the factory soldering job. Soldering the wires back on
is a little tricky due to their thin nature. The plastic body of the
power connection means that care in soldering is required or you will
melt and deform the connector.
Tightening the connector was also required as it had backed out and
almost fallen into the case. In this case, the outer
ring of the connector screws onto the connector body inside the clock,
thusly holding everything together tighlty. Two notches in the outer
ring allow it to be tightened or loosened as though it were a screw. A
very small side cutters served as an effective device to fasten or
loosen the outer ring. While it may loosen again, the ring was fastened
very tightly. At least the little outer ring hadn't disappeared
If you need a new connector, it is important that the replacement
connector contains a sping-loaded disconnect that severs the connection
between battery and power adapter ground. This probably isn't crucial,
but the designers included it for a reason...so you should do so as
Replacement Projection Bulb
There is no helpful legend to tell you what kind of bulb should be used
for a replacement in these clocks. If you're lucky, the
correct-but-burned-out bulb will still be in your clock, and you may
simply buy another of the same type.
I was not that lucky. One of my clocks didn't have a bulb at all, and
the other had a PR30 bulb. And I assumed that its previous owners
hadn't messed with it! Silly me, making such an assumption and getting
a PR30 bulb for this clock!
The PR30 is completely unsuitable for this application. Although the
voltage rating for this bulb (3.75 volts) strikes a fair balance
between what the power adapter puts out and what the batteries can
supply (ensuring that--in theory--the bulb will light reasonably well
on either power source) it pulls some 860mA per its rating. You'll blow
away most batteries with this kind of current draw if you request a
time projection for anything beyond the shortest possible interval.
This also makes the little Hoyle wall-wart power adapter very
unhappy. In addition to getting VERY hot, the power adapter didn't have
to oomph to light the PR30 bulb to nearly enough intensity to make the
projection usable. I really thought the wall-wart was bad until I
noticed that it didn't get anywhere near as hot without the clock
plugged in. Oops.
The clock based on the knock-off IC also tended to reset itself
whenever the snooze bar was pushed. This is not surprising considering
what probably happened to the IC's supply voltage whenever the bulb lit
It seems that what you really want is a PR17 bulb. This bulb comes
about as close as you can to the 4.5 volt, 300mA rating of the Hoyle
power adapter, with the bulb having a 4.9 volt rating and current draw
of 300mA. The projection is entirely readable in even a moderately lit
room, and this bulb still shines brightly enough with the batteries in
place that you can still use the temporary projection function that is
built into the snooze bar. Since the bulb will be spending a lot of
time turned on, the slightly higher voltage rating should prolong its
life in this application.
If you know of a better replacement bulb, please let me know. I wrote Brown & Bigelow and never
got a reply from them.
There is also a "grain of sand" bulb (maybe two of them) in the main
display to light it up at the edges. It too comes on when the snooze
bar is pressed.
The "Wall Wart" (or plug-in
These clocks utilize a 4.5 volt DC,
outer tip positive
power adapter with a connector just like that of an audio miniplug,
rated at 300 milliamps. (If
you needed to find a replacement, a monophonic earphone jack would
probably work fine. Just try to get one that will disconnect the
negative battery lead when the connection is made.
You might have to "assemble" your own wall wart if you need one.
The regulation on the original Hoyle power adapter is not particularly
good when unloaded--I tested the unloaded adapter and got voltage
readings well in excess of eight volts DC.
Both of these neat clocks are running again, and they project the time
perfectly with their new light bulbs. If
you've read down this far, I appreciate your taking the time do so, and
would like to hear what you have to think
about this page.
Also, if you know approximately how old these clocks are, I'd certainly
like to know.
All I can say with regard to their age is that my grandparents had them
for as long as I can remember. The only clue I've seen is printed on
one of the power adapters--the numbers "81 13" appear on it. I take
them to mean the 13th week of the year 1981.
Thank you for listening today. Now, if you'll pardon me, I have to go
find another clock!
2009-10 William R.
Walsh. All Rights Reserved. Written 11/09/2009. Updated 12/03/2009 and
again on 02/27/2010.
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