Ok, This One Is Strange. I need A Flip-Dot Driver Circuit

[Tim]

I have a few old flip-dot displays that I would like to drive from a TTL
source. I know they need a bi-polar power control to accomplish the
task. Basically these displays will flip the dot over with power in one
direction and flip ot back when the leads are reversed. The cycle just
needs a pulse to flip the dot, as it will stay flipped until the reverse
power is applied.

I did find 1 reference on the net, but it did not go into detail about
the actual driver design.

This is a project for later in life, but I thought I would start
collecting info now.

Any helpful info is always appreciated....

Thanks

- Tim -

 

[Hal Murray]

I have a few old flip-dot displays that I would like to drive from a TTL
source. I know they need a bi-polar power control to accomplish the
task. Basically these displays will flip the dot over with power in one
direction and flip ot back when the leads are reversed. The cycle just
needs a pulse to flip the dot, as it will stay flipped until the reverse
power is applied.

Do you have a handful of individual cells that are 1 dot each
with 2 wires coming out? Or do you have a module with lots of
dots and a few wires coming out?

If the latter, the unit probably includes the drivers and you
talk to it with RS-232 or similar.

If you have a handful of individual dots, you need to figure
out how much current they take and what voltage. You can probably
experiment with a battery and resistors.

If you want more than a single dot, I'd expect the simple way
to go is to put them in a matrix. You have horizontal and
vertical wires. Put a dot at each intersection and connect
one lead from the dot to the horizontal wire and the other to
the vertical wire.

Then you need 2 drivers for each wire. One pulls up. The other
pulls down. If neither is on the wire floats. You can probably
get that with a transistor and resistor for each driver if the
current is low enough.

Do set a dot, you pull up on one wire and down on the other of
the pair that intersects at the dot. To unset it, reverse up
and down.


--
These are my opinions, not necessarily my employer's. I hate spam.

 

[Tim]

In article <ddqdncXoTuuTZK_bnZ2dnUVZ_q3inZ2d@megapath.net>, hal-
usenet@ip-64-139-1-69.sjc.megapath.net says...

I have a few old flip-dot displays that I would like to drive from a TTL
source. I know they need a bi-polar power control to accomplish the
task. Basically these displays will flip the dot over with power in one
direction and flip ot back when the leads are reversed. The cycle just
needs a pulse to flip the dot, as it will stay flipped until the reverse
power is applied.

Do you have a handful of individual cells that are 1 dot each
with 2 wires coming out? Or do you have a module with lots of
dots and a few wires coming out?

If the latter, the unit probably includes the drivers and you
talk to it with RS-232 or similar.

If you have a handful of individual dots, you need to figure
out how much current they take and what voltage. You can probably
experiment with a battery and resistors.

If you want more than a single dot, I'd expect the simple way
to go is to put them in a matrix. You have horizontal and
vertical wires. Put a dot at each intersection and connect
one lead from the dot to the horizontal wire and the other to
the vertical wire.

Then you need 2 drivers for each wire. One pulls up. The other
pulls down. If neither is on the wire floats. You can probably
get that with a transistor and resistor for each driver if the
current is low enough.

Do set a dot, you pull up on one wire and down on the other of
the pair that intersects at the dot. To unset it, reverse up
and down.



Actually these units were in a display for a toll booth. I intended to

take the matrixes apart to make individual segments out of them. So the
end display would be like a big LED one, only with a bank of 7 flip dots
for each segment. The displays are currently in a 5x7 matrix on boards,
but I can easily break up the matrix to make my segments out of.

The actual 1x7 elements are BUSE BM-70. I did have the power
requirements at one time. I seem to recall I figured it out to be 5 v at
at about 100 ma or so. I guess my problem is how to get the lines to
reverse polarity using TTL logic.

I have a score keeper that I built using hi-brite LEDs, but they are not
bright enough for sunny day use, so I figured I could put these elements
in instead.

Thanks,

- Tim -

 

[Gary Tait]

Tim <tim@tim.tim> wrote in news:MPG.209c7c9814af1ce989760
@allnews.nbnet.nb.ca:

I have a few old flip-dot displays that I would like to drive from a
TTL
source. I know they need a bi-polar power control to accomplish the
task. Basically these displays will flip the dot over with power in
one
direction and flip ot back when the leads are reversed. The cycle just
needs a pulse to flip the dot, as it will stay flipped until the
reverse
power is applied.

I did find 1 reference on the net, but it did not go into detail about
the actual driver design.

This is a project for later in life, but I thought I would start
collecting info now.

Any helpful info is always appreciated....

Thanks

- Tim -

You want an H-bridge. They are commonly used to control DC motors with
logic signals. If not much current is needed, you might be able directly
drive them with the right buffer IC.

 

[Tim]

In article <Xns99209C286344Fwonkynillmailnil@142.77.1.194>,
classicsat@yahoo.com says...

Tim <tim@tim.tim> wrote in news:MPG.209c7c9814af1ce989760
@allnews.nbnet.nb.ca:

I have a few old flip-dot displays that I would like to drive from a
TTL
source. I know they need a bi-polar power control to accomplish the
task. Basically these displays will flip the dot over with power in
one
direction and flip ot back when the leads are reversed. The cycle just
needs a pulse to flip the dot, as it will stay flipped until the
reverse
power is applied.

I did find 1 reference on the net, but it did not go into detail about
the actual driver design.

This is a project for later in life, but I thought I would start
collecting info now.

Any helpful info is always appreciated....

Thanks

- Tim -


You want an H-bridge. They are commonly used to control DC motors with
logic signals. If not much current is needed, you might be able directly
drive them with the right buffer IC.

Yup I remember that 4 transistor setup from before. I found a bunch of

references on the net about that, so I'll do some digging for a bit..

Thanks for the info.....

- Tim -

 

[Tim]

In article <Xns99209C286344Fwonkynillmailnil@142.77.1.194>,
classicsat@yahoo.com says...

Tim <tim@tim.tim> wrote in news:MPG.209c7c9814af1ce989760
@allnews.nbnet.nb.ca:

I have a few old flip-dot displays that I would like to drive from a
TTL
source. I know they need a bi-polar power control to accomplish the
task. Basically these displays will flip the dot over with power in
one
direction and flip ot back when the leads are reversed. The cycle just
needs a pulse to flip the dot, as it will stay flipped until the
reverse
power is applied.

I did find 1 reference on the net, but it did not go into detail about
the actual driver design.

This is a project for later in life, but I thought I would start
collecting info now.

Any helpful info is always appreciated....

Thanks

- Tim -


You want an H-bridge. They are commonly used to control DC motors with
logic signals. If not much current is needed, you might be able directly
drive them with the right buffer IC.

Hi again, I think I have found a solution using your information. I came

across a chip made by Maxim the MAX4424 series. I also found real world
circuits using this unit to drive DC motors. I have asked for some
samples to see if they will works with my application, but I have to
wait for "factory approval" for them to ship. I am expecting a very high
failure rate while I am getting the mix down just right.

If this works out, I will use 1 chip, 2 resistors and maybe 4 diodes per
segment of my display. I will need quite a few of them, but I can buy
them in small amounts until I have enough.

Thanks for your help in getting me started...

- Tim -