kline@tuna.cso.uiuc.edu (Charley Kline) (06/06/89)
Having recently been promoted to assistant Technical Director at
the local community theater, and being the only person there with
a degree in an engineering discipline, naturally the "neat gizmo"
wishlist fell to me. Top on the TD's list is a box which will
perform some complicated sequencing of lighting.
Now, I've had as much logic design as the next guy, so the
sequencing part is easy (shift registers and such). Where my
knowledge of how electrons in silicon behave is sorely lacking is
in the part that's going to have to take the delicate little TTL
signal from my shift register and use it to turn on and off a
1500-watt lighting instrument. A mechanical relay is right out
because our tech booth is right next to the audience and has no
sound insulation to speak of. So this thing is going to have to
operate silently.
I recall from the elemental projects I built in high school that
there's this thing called a triac which is essentially two SCR's
in parallel and facing opposite directions. I figure this is what
I want to use (but please correct me if I'm wrong). The problem
is that I have no idea how to connect this thing. What, just put
the load in series with the main terminals of the triac and con-
nect the gate to the TTL signal? Surely not. And I looked in the
Newark catalog under "Triacs" and they had a million of them, all
rated by "RMS", "Itsm", four different kinds of "Igt" and "Vgt",
and "Vgrm".
Can someone help me with these numbers and tell me how to connect
one? Thanks in advance!
In a related vein, I remember seeing some talk here from people
who were doing technical theater projects. Who are you all? I'm
on a rampage to evolve our VERY low-tech theater into the 1990's,
and I could use some good ideas as well as some technical gui-
dance, because as I say, I'm not much good at high-energy elec-
tronics. And besides, us technical theater nerds should hang out
together anyway. :)
-----
Charley Kline, University of Illinois Computing Services
kline@tuna.cso.uiuc.edu
{uunet,seismo,pur-ee,convex}!uiucdcs!uiucuxc!kline
"They always said I would be nothing but a fish head. And look at me now."henry@utzoo.uucp (Henry Spencer) (06/07/89)
In article <1164@garcon.cso.uiuc.edu> kline@tuna.cso.uiuc.edu (Charley Kline) writes: >... What, just put >the load in series with the main terminals of the triac and con- >nect the gate to the TTL signal? Surely not... A good place to start on this would be to get spec sheets and applications notes on the 3011 (formally the MOC3011, I think) from Motorola or some other source of it. This is really what you want for such a job: a small triac with an opto-isolated control input, which can be used to control bigger triacs. Good isolation is quite important when you have kilowatts of AC on one side and TTL on the other side! You also might want to look at "solid-state relays", available from many suppliers, which are essentially fancy pre-packaged versions of all that. These things really can take TTL (or whatever) in one side and control heavy-duty AC on the other side. They will, of course, cost more than buying triacs and building it yourself. Might be preferable if you are interested in getting fairly-standard results quickly rather than in learning or custom effects, though. -- You *can* understand sendmail, | Henry Spencer at U of Toronto Zoology but it's not worth it. -Collyer| uunet!attcan!utzoo!henry henry@zoo.toronto.edu
gil@limbic.UUCP (Gil Kloepfer Jr.) (06/07/89)
In article <1164@garcon.cso.uiuc.edu> kline@tuna.cso.uiuc.edu (Charley Kline) writes: >in the part that's going to have to take the delicate little TTL >signal from my shift register and use it to turn on and off a >1500-watt lighting instrument. A mechanical relay is right out [...] >there's this thing called a triac which is essentially two SCR's >in parallel and facing opposite directions. I figure this is what >I want to use (but please correct me if I'm wrong). The problem >is that I have no idea how to connect this thing. A good (and my favorite way) to hook high voltage stuff to a low voltage circuit, like TTL, without the potiential of frying my TTL circuit is to isolate the two circuits using what is called an "opto isolator". This is a chip with a LED and phototransistor placed back-to-back. You hook the LED to the TTL circuit (via a current-limiting resistor, of course :-) and use the transistor on the other side to send a signal to some high current/voltage passive device. I'm not sure exactly how this would be connected in your application, but I definitely wouldn't hook TTL directly to a semiconductor which is connected to house current (except in a switching supply...or something like that...). >Charley Kline, University of Illinois Computing Services >kline@tuna.cso.uiuc.edu >{uunet,seismo,pur-ee,convex}!uiucdcs!uiucuxc!kline ----- | Gil Kloepfer, Jr. | ICUS Software Systems/Bowne Management Systems (depending on where I am) | {icus,lilink}!limbic!gil or gil@icus.islp.ny.us
heller@algol.crd.ge.com (aaron j heller) (06/10/89)
In article <1164@garcon.cso.uiuc.edu> kline@tuna.cso.uiuc.edu (Charley Kline) writes: ... >the part that's going to have to take the delicate little TTL >signal from my shift register and use it to turn on and off a >1500-watt lighting instrument. A mechanical relay is right out ... There is a device called a solid state relay. I used a few of them about 10 yrs. ago for a similiar application. They are a combination of an opto-isolator and triac. Some of them also have zero-crossing detectors built in to minimize RFI problems. Check the Newark catalog. Aaron Heller (heller@crd.ge.com uunet!crdgw1!heller)
wte@ncrcae.Columbia.NCR.COM (Bill Eason) (06/10/89)
In article <505@limbic.UUCP> gil@limbic.UUCP (Gil Kloepfer Jr.) writes: >In article <1164@garcon.cso.uiuc.edu> kline@tuna.cso.uiuc.edu (Charley Kline) writes: >>in the part that's going to have to take the delicate little TTL >>signal from my shift register and use it to turn on and off a >>1500-watt lighting instrument. A mechanical relay is right out >[...] >>there's this thing called a triac which is essentially two SCR's >>in parallel and facing opposite directions. I figure this is what >>I want to use (but please correct me if I'm wrong). The problem >>is that I have no idea how to connect this thing. > >A good (and my favorite way) to hook high voltage stuff to a low voltage >circuit, like TTL, without the potiential of frying my TTL circuit is >to isolate the two circuits using what is called an "opto isolator". >This is a chip with a LED and phototransistor placed back-to-back. Someone mentioned the Motorola MOC 3031, I believe, but I would like to put in my $.02 worth on this. Motorola has a whole family of these devices. In my EE senior project, we used the MOC 3010 (I think), which is an 8-pin chip with a TTL-drivable LED on one side and a low-power-handling triac on the other side. The low-power triac can then be used to trigger the gate on a high-power triac. Radio Shack sells the 3010 complete with their little circuit for this setup on the back of the package. One point to note, though, they give two circuits: one for triggering an inductive load and one for a resistive load. We were controlling the power to a 500W slide projector bulb, and I believe we used the circuit for a resistive load. You may want to check this if you decide to go this route. A little extra circuitry (which we used, too) will let you control the percentage of power to the bulb instead of just turning it full-on or full-off. A little more circuitry will let you control this from a digital value (8 bits = 256 brightness levels). Email for more info. -wte -- Bill Eason (803) 791-6419 ...!ucbvax!sdcsvax!ncr-sd!ncrcae!sauron!wte NCR Corporation ....!rutgers!mcnc!ece-csc!ncrcae!sauron!wte E & M Columbia 3325 Platt Springs Rd. West Columbia, SC 29169
john@frog.UUCP (John Woods) (06/15/89)
In article <505@limbic.UUCP>, gil@limbic.UUCP (Gil Kloepfer Jr.) writes: > this would be connected in your application, but I definitely wouldn't > hook TTL directly to a semiconductor which is connected to house current Haven't you ever used a WAS gate? 115 vac | |14 -------\ | 7400 |o -------/ |7 | 115 vac -- John Woods, Charles River Data Systems, Framingham MA, (508) 626-1101 ...!decvax!frog!john, john@frog.UUCP, ...!mit-eddie!jfw, jfw@eddie.mit.edu People...How you gonna FIGURE 'em? Don't bother, S.L.--Just stand back and enjoy the EVOLUTIONARY PROCESS...
rzh@lll-lcc.UUCP (Roger Hanscom) (06/16/89)
In <1507@frog.UUCP> john@frog.UUCP (John Woods) says:
[stuff deleted....]
>Haven't you ever used a WAS gate?
>
> 115 vac
> |
> |14
> -------\
> | 7400 |o
> -------/
> |7
> |
> 115 vac
>
Shouldn't that be?
115 vac ^
| / ^
|14 / / ^
-------\ / /
| 7400 |o /
-------/
|7
|
115 vac
Is that a LETTL?? (ascii circuits are hell!) @:^)
roger rzh%freedom.llnl.gov@lll-lcc.llnl.gov
{uunet,ames,ucbvax,..}!lll-lcc!freedom!rzh
Upstairs, Over a Vacant Lot, Inc.gil@limbic.UUCP (Gil Kloepfer Jr.) (06/18/89)
In article <1507@frog.UUCP> john@frog.UUCP (John Woods) writes: >Haven't you ever used a WAS gate? > > 115 vac > | > |14 > -------\ > | 7400 |o > -------/ > |7 > | > 115 vac > Personally, I like this one. This is a TTL thermo-gate. It produces a high temperature when activated: 7 +------+ 14 +5 ----+ 7400 +----- GND +------+ Never give a screwdriver to a programmer ;-) ------- | Gil Kloepfer, Jr. | ICUS Software Systems/Bowne Management Systems (depending on where I am) | {icus,lilink}!limbic!gil or gil@icus.islp.ny.us