Purposed circuit.

[More Coffee]

Im making a simple sequencer for some Christmas lights..to iluminate a tree of lights essentially..

Based in the Knight Rider circuit..the sequencer will offer CW/CCW and alternating conditions via an on/on/on switch..
The problem is,I only have one 74LS154, being green and unsure Im hoping the circuit below will engage the relay,and not damage the 74LS154.
The relay is 12v. switched on by the 2n3906 using the 5v output of the 74ls154.


Thanks for any input!!

 

[4pyros]

It should work but the base resister seems a little high you may have to adjust it down.

 

[Reloadron]

You don't mention how you plan to drive the 74154 4 line to 16 line decoder?

Given a choice I would drive the decoder using a 74193 4 bit up/dn counter. Then control direction on the counter using a simple SPDT switch (or electronically). I would not use relays but would likely use the 74154 to drive MOC3010 (data sheet to be found here). Get a bunch of SCRs rated for maybe 400 V and a few amps for the MOC3010 to drive. The data sheet covers it.

<EDIT> Oh before I forget, drive the 74193 with a simple 555 oscillator for adjustable speed. </EDIT>

Ron

 

[Roff]

You don't mention how you plan to drive the 74154 4 line to 16 line decoder?

Given a choice I would drive the decoder using a 74193 4 bit up/dn counter. Then control direction on the counter using a simple SPDT switch (or electronically). I would not use relays but would likely use the 74154 to drive MOC3010 (data sheet to be found here). Get a bunch of SCRs rated for maybe 400 V and a few amps for the MOC3010 to drive. The data sheet covers it.

<EDIT> Oh before I forget, drive the 74193 with a simple 555 oscillator for adjustable speed. </EDIT>

Ron

SCRs don't work with AC. He'll need triacs. See Fig. 7 of the MOC3010 datasheet for application schematic.
Also, see Fairchild Application Note AN-3003
Applications of Random Phase Crossing Triac Drivers

EDIT: 74xx191 might be easier to use. 74xx193 has separate up and down clock pins. 74xx191 has a single clock pin and a separate up/down control pin.

 

[Reloadron]

My bad as I should have said Triac when referencing the MOC3010. However, SCRs do in fact work just fine with AC the difference being since a SCR is unidirectional you only get to use the positive portion of the AC waveform. I would not make the statement:

SCRs don't work with AC.

I do agree the 74191 would be a better choice requiring less steering logic for the clock. Good call.

Ron

 

[4pyros]

My bad as I should have said Triac when referencing the MOC3010. However, SCRs do in fact work just fine with AC as can be seen here the difference being since a SCR is unidirectional you only get to use the positive portion of the AC waveform. I would not make the statement:

Yes SCRs are used in AC to DC motor controllers and battery charger controllers stright off AC.

 

[More Coffee]

Thanks guy's.
Ive already built the circuit on the bread board using a
555 timer
7476 J/K flip flop
74191
and the 74LS154.
My bad I just assumed that it would be concluded that the circuit was already functioning ,and that I was trying to manipulate the outputs from the 74154.

Generally one full count would take between 4-6 seconds,I have to mess with the Capacitor on the 555 to dial it down a little more with the potentiometer., I have the relays on hand and they were free ,PCB mount type and rated for 10amp@120V A/C, .. on the contacts ,,, one set of 100 leds draws 63 watt's(according to the manufacturer) which if my math is correct,that's 525,milliamp per string . I did not think that the arcing would be that bad.
Each string will be plugged into a duplex receptacle with the hot split,so each receptacle will be two channels,each turned on by its allocated relay..
I understand that the relays will not withstand a whole lot of cycling, Knowing this I just didn't want to tear up the circuit..while i waited for something more solid state to pop up cheap or free.
Not to be smart or brazen ,,but i really dont uderstand why relay's would not be a good choice..other than its longivity and noise

I have absolouty no experience with opto's or SCR's..
I have a few opto's and maybe a couple od SCR's in my bits box..Anybody suggest a simple project to build up a little hands on and experience ..it would be appreciated.

 

[4pyros]

[QUOTEbut i really dont uderstand why relay's would not be a good choice..other than its longivity and noise

][/QUOTE]
Thats all you hit the nail on the head.

 

[4pyros]

Anybody suggest a simple project to build up a little hands on and experience ..it would be appreciated.

Look for "triac circuits".

 

[Roff]

My bad as I should have said Triac when referencing the MOC3010. However, SCRs do in fact work just fine with AC the difference being since a SCR is unidirectional you only get to use the positive portion of the AC waveform. I would not make the statement:



I do agree the 74191 would be a better choice requiring less steering logic for the clock. Good call.

Ron

That's a valid point. If you want a combination switch and bulb-saver, use SCRs.

 

[More Coffee]

triac circuits..10-4!!

 

[Reloadron]

Not to be smart or brazen ,,but i really dont uderstand why relay's would not be a good choice..other than its longivity and noise

My suggestion as to using a SCR (not the best) and later a Triac (much better for your application) was merely my thinking on the how to do it.

Not to say it is the better or best way to go about it. I would go that route for the very reasons you mentioned. Especially circuit noise with a little collection of flyback diodes trying to snub the inductive kick from the relays. Actually I just seem to have this love affair with actually Solid State Relays.

Ron

 

[audioguru]

I thought you are foreign which is why you are using old fashioned TTL logic ICs and old fashioned incandescent Christmas tree lights.

But in my part of Canada the electrical utility company gave away LED Christmas tree lights for free! when we exchanged an old incandescent set of lights. Now I have many strings of modern low power LED Christmas tree lights. All my old incandescent Christmas tree lights have been traded in.

 

[Reloadron]

old fashioned incandescent Christmas tree lights

Hey, I use C7 bulbs because I like an old fashioned Christmas!

Ron

 

[audioguru]

An old fashioned incandescent light bulb draws 10 times or more its normal current when it turns on because the resistance of its filament is much higher when at 2000 degrees C.

LED Christmas tree lights are a joke because they are so dim. They also flicker on and off at 120Hz here (100 Hz in Europe?)

 

[4pyros]

when we exchanged an old incandescent set of lights.

They will soon be a collectors item and worth good money and you don't have any.

 

[4pyros]

LED Christmas tree lights are a joke because they are so dim. They also flicker on and off at 120Hz

They gave you cheep LED lights then.

 

[audioguru]

They gave you cheep LED lights then.

Cheep (cluck, cluck, quack, quack) lights are made with Chinese LEDs. I was talking about cheap LEDs that are also made in China but are extremely poor quality. The strings of LEDs for Christmas trees do not have a rectifier nor RC filter so they flicker on and off and look dim.

 

[Reloadron]

An old fashioned incandescent light bulb draws 10 times or more its normal current when it turns on because the resistance of its filament is much higher when at 2000 degrees C.

LED Christmas tree lights are a joke because they are so dim. They also flicker on and off at 120Hz here (100 Hz in Europe?)

Yeah, and that last how long? The tree is on an average of maybe 5 hours a day so if I take a few hundred C7 bulbs that reach temperature in what? Some milliseconds how exactly does that pail in the big scheme of several hours of on time? I like my old but nostalgic bulbs and I don't like the new and improved bulbs. My tree and my bulbs!

Anyway, this is going off topic and we don't want to do that. We could start a belated Christmas Lights thread in the off topic areas. Be it belated or real damn early.

Ron

 

[More Coffee]

Extremely cheap..


audioguru


I thought you are foreign which is why you are using old fashioned TTL logic ICs and old fashioned incandescent Christmas tree lights.

No not foreign, just cheap..LOL.. I'm not to much for writing code when all I want is set and forget,with some minor maintenance..I don't mind popping a relay in from time to time..

The last time I was considered a foreigner I was at the DMV in Oakville,Ontario and a "New Canadian" insisted I produce a passport to prove I'm allowed in Canada and I have the right papers to get my drivers licence changed to an Ontario license..I snapped..I lost it.. He called his supervisor ,explained that I had all the wrong paper work and no passport to prove I was allowed in Canada..

The supervisor quickly took me around the counter and handled my case personally..in 10 minutes I had my license..no fee's.
So to suggest i may be foreign to this country I was born and raised in I take some offense.