[linnix]

We deal directly with the factory. The "standard parts" are for

Do you guys always spec LCDs with pins instead of rubber contacts? I
found rubber contacts not to be too reliable. The other issue is ESD
even if there is plastic film in front. A wee bit too much displacement
current while the uC is off and bzzzt, there goes the substrate diode
and that LCD section is dead.

Yes, pins (~ 1 cent each) are far more reliable. For 60 cents LCD, we
don't need to cut corners. We use x4 to lower the pin counts.
Unfortunately, AVR (or most uC) can't do x6 or x8. We might use 8x8
eventually, with a custom controller chip.

 

[Joerg]

Yes, pins (~ 1 cent each) are far more reliable. For 60 cents LCD, we
don't need to cut corners. We use x4 to lower the pin counts.
Unfortunately, AVR (or most uC) can't do x6 or x8. We might use 8x8
eventually, with a custom controller chip.

1c is a very small price to pay for the reliability advantage that pins
afford.

 

[Spehro Pefhany]

Yes, pins (~ 1 cent each) are far more reliable. For 60 cents LCD, we
don't need to cut corners. We use x4 to lower the pin counts.
Unfortunately, AVR (or most uC) can't do x6 or x8. We might use 8x8
eventually, with a custom controller chip.

The higher you go with mux ratio the more you have to worry about low
contrast and contrast shifts with temperature. I think x3 or x4 is
pretty trouble-free.


Best regards,
Spehro Pefhany

 

[Spehro Pefhany]

1c is a very small price to pay for the reliability advantage that pins
afford.

1 cent per pin.
Best regards,
Spehro Pefhany

 

[Joerg]

1 cent per pin.
Best regards,
Spehro Pefhany

Understood. Still, a small price on a 4-MUX LCD.

 

[linnix]

The higher you go with mux ratio the more you have to worry about low
contrast and contrast shifts with temperature. I think x3 or x4 is
pretty trouble-free.

The customer is happy with x4, even for outdoor direct sun-light
viewing. But we might run out of display elements. We might need to
group the "clock features" into a separate common. Namely, the first
digit as 0 or 1, AM/PM and colon. Since they are not needed for other
functions, we can hardwire the switch between commons.

1 2 3 4a for clock
1 2 3 4b for everything else

We are still working out the design. When it's ready, everybody here
can get a free sample.

 

[linnix]

Linnix,




Can you tell us what the application is for your LCD there? (I believe you
said you've already sold a bunch of the older design...)

The device has an AVR (Atmega169) with a 12x4 LCD and four buttons.
The uC interface with a custom sensor and display data on the LCD.
The buttons can do some simple config and setup. It is approximately
3 inches x 1 inch.

However, we believe that if we put it in the form of a watch (1 sq.
in.), it will have better market exposure. Furthermore, if we reuse
the LCD in other projects, we can get better economy of scale.

Would you like to have a multimeter watch?

 

[Jan Panteltje]

The device has an AVR (Atmega169) with a 12x4 LCD and four buttons.
The uC interface with a custom sensor and display data on the LCD.
The buttons can do some simple config and setup. It is approximately
3 inches x 1 inch.

However, we believe that if we put it in the form of a watch (1 sq.
in.), it will have better market exposure. Furthermore, if we reuse
the LCD in other projects, we can get better economy of scale.

Would you like to have a multimeter watch?

What about probes?
What about if you want to measure 500V floating, the isolation.
I like to keep multimeter clear from myself in some cases.

 

[Spehro Pefhany]

The device has an AVR (Atmega169) with a 12x4 LCD and four buttons.
The uC interface with a custom sensor and display data on the LCD.
The buttons can do some simple config and setup. It is approximately
3 inches x 1 inch.

However, we believe that if we put it in the form of a watch (1 sq.
in.), it will have better market exposure. Furthermore, if we reuse
the LCD in other projects, we can get better economy of scale.

Would you like to have a multimeter watch?

Sounds intriguing if not too huge, and reasonably functional (find
some way to store probes within?). Safety concerns need to be
addressed.

Best regards,
Spehro Pefhany

 

[linnix]

What about probes?

That would have to be external, may be a finger tip cap.

What about if you want to measure 500V floating, the isolation.
I like to keep multimeter clear from myself in some cases.

There are certainly limitations, but most people just want to measure
batteries anyway.

 

[Joerg]

The device has an AVR (Atmega169) with a 12x4 LCD and four buttons.
The uC interface with a custom sensor and display data on the LCD.
The buttons can do some simple config and setup. It is approximately
3 inches x 1 inch.

However, we believe that if we put it in the form of a watch (1 sq.
in.), it will have better market exposure. Furthermore, if we reuse
the LCD in other projects, we can get better economy of scale.

Would you like to have a multimeter watch?

Now that would be the ultimate nerd tool!

However: Do your corporate lawyers know about this idea? Did they need
heart medication and Maalox after learning about the idea? Just imagine
uncle Leroy whipping out a couple of probe cables, sticking them in
somewhere on his wrist, then reaching into his neighbor's gas furnace to
see if the 240VAC is still there.

 

[Spehro Pefhany]

Now that would be the ultimate nerd tool!

However: Do your corporate lawyers know about this idea? Did they need
heart medication and Maalox after learning about the idea? Just imagine
uncle Leroy whipping out a couple of probe cables, sticking them in
somewhere on his wrist, then reaching into his neighbor's gas furnace to
see if the 240VAC is still there.

Could be limited to 12V or 14.99V or something like that. And a
non-conductive case.
Best regards,
Spehro Pefhany

 

[linnix]

Now that would be the ultimate nerd tool!

However: Do your corporate lawyers know about this idea? Did they need
heart medication and Maalox after learning about the idea? Just imagine
uncle Leroy whipping out a couple of probe cables, sticking them in
somewhere on his wrist, then reaching into his neighbor's gas furnace to
see if the 240VAC is still there.

Well, I would at least remove the watch from my wrist first. The
point is not to have to carry another meter. You don't have to use it
in place (your wrist).

 

[Joerg]

Could be limited to 12V or 14.99V or something like that. And a
non-conductive case.

Yes, but you know how that goes. "Oh, let's see if the uC on the gas
furnace controller has juice on VCC... oops!" ... bzzzt ... *BANG*.

 

[Joerg]

Well, I would at least remove the watch from my wrist first. The
point is not to have to carry another meter. You don't have to use it
in place (your wrist).

Sure, but there is always that one stupid user. If it doesn't say "Do
not put in mouth" in multiple languages you could be in trouble already.
I've seen my share of careless folks. Like when someone checked the
water level in his car battery, peeking inside, with a cigarette loosely
dangling between his lips.

 

[Spehro Pefhany]

Yes, but you know how that goes. "Oh, let's see if the uC on the gas
furnace controller has juice on VCC... oops!" ... bzzzt ... *BANG*.

If it's just a voltmeter, put a M or two in series with each probe
wire. Same risk level as an ESD wristband (almost zero).
Best regards,
Spehro Pefhany

 

[Joerg]

If it's just a voltmeter, put a M or two in series with each probe
wire. Same risk level as an ESD wristband (almost zero).

That would be good. But it doesn't cover the real brazen guys who place
alligator clips first and then fumble it all into the wrist watch meter ;-)

Seriously, I've seen a guy who started a car, unclipped the jumper
cables from the helper car so the other guy could head off to the
hardware store and left the now hot cables laying on the garage floor
while revving his engine.

 

[Joerg]

What's your point?

;-)

The same that the lawyers make in cases where someone poured hot coffee
over themselves and then sued. Unfortunately. I don't like it that
people are financially rewarded for their stupidity by a jury but that's
the way it often is right now.

 

[Mike Harrison]

The device has an AVR (Atmega169) with a 12x4 LCD and four buttons.
The uC interface with a custom sensor and display data on the LCD.
The buttons can do some simple config and setup. It is approximately
3 inches x 1 inch.

However, we believe that if we put it in the form of a watch (1 sq.
in.), it will have better market exposure. Furthermore, if we reuse
the LCD in other projects, we can get better economy of scale.

Would you like to have a multimeter watch?

Yes.
I think there is a gap in the market for a really small basic DMM, with well designed sensibly small
leads/probes, as part of a 'minimum size' general purpose toolkit.
Many (20?) years ago I got a pen type DMM by Pantec, and have yet to see anything smaller, despite
subsequent improvements in technology ( cheap, low-power MCUs).

 

[Joerg]

Yes.
I think there is a gap in the market for a really small basic DMM, with well designed sensibly small
leads/probes, as part of a 'minimum size' general purpose toolkit.
Many (20?) years ago I got a pen type DMM by Pantec, and have yet to see anything smaller, despite
subsequent improvements in technology ( cheap, low-power MCUs).

You can still buy small meters but it seems you can't buy them at higher
prices and good quality. They range from $2.99 at Harborfreight to $25
or so for a small pen style. But then the inevitable happens. On my pen
meter the slider switch is giving up because it just scrapes on the
circuit board.

Those cheap Harborfreight meters are holding up surprisingly well so
far. I took one apart to see how they did it and that's really the
ultimate in cost reduction. It's always a learning experience. The only
not so nice thing about them is the ugly pink/purple color.