creating timing circuit

[oreoweb6]

I need help. I have a star christmas lantern (little over 2 feet) but one of the timers went bad. My lantern uses (110v) 5 25 watt bulbs on one timer and 1 25 watt bulb on another timer. When one set comes on the other goes off. A friend found the problem and tried to replace a diode that burned out because of the timer but as the power went on the diode instantly smoked (hes inexperinced in timers. only knows radio). the timer is very small. So i figure it be better to replace it somehow. The timer circuit is so small it fits easily inside of a 35mm camera film canister (thats its storage housing). I have not taken electronics since middle school but put together a ac-dc converter by myself. any help or suggestion would be much appreciated.

 

[Reloadron]

Doesn't sound too complicated. I would venture a guess of a few SSR circuits along these lines and driven by a simple clock circuit. The SSR circuits would be toggled. How much time were they on/off?

Ron

 

[oreoweb6]

Timiing

Thanks for reply ron. It appear the center single light is on for .23 of a second and off for just about a second. Im very unfamilar with timing circuits. its such a beautiful and expensive lantern to throw away because of a timing circuit.

 

[Reloadron]

OK, don't think I have forgotten the thread. Hopefully this evening I'll post a few ideas and a circuit.

Ron

 

[Reloadron]

The attached image is one possible solution. I would replace R2 with a 500 K ohm pot to give some range adjusting the times but it is close as it is drawn. Out 1 and Out 2 would go to small triac circuits like I already linked to. We use the output of the 555 timer and we also use a transistor to invert that same output. The outputs toggle. Any questions just ask.

A simpler method would be to program a single tiny PIC uController but as to discreet components the attached should give the results you want.

Ron

 

[Shyamal]

For timing circuit, 555ic is the best ic. Using this ic, timer circuit making is too easy.

 

[oreoweb6]

wiring diagram

Thanks. I saw the diagram but I only have one input into the timer and out to the rest of the lights. Is this how this timer works? I saw before signing onto this site about the 555 timer.

 

[Reloadron]

The circuit I posted uses 2 outputs. One for the outer lights and one for the center light(s). I based it on this:

I have a star christmas lantern (little over 2 feet) but one of the timers went bad. My lantern uses (110v) 5 25 watt bulbs on one timer and 1 25 watt bulb on another timer. When one set comes on the other goes off.

Thinking about it a single out timer could be used driving a small relay switching the 120 VAC to one set or the other set of lights. The relay would be a SPDT (Single Pole Double Throw) type. Pretty much a matter of how you want to go about it.

Ron

 

[oreoweb6]

ok..so I need only one circuit board to run both sets instead of the 2 seperate boards..thats better than i expected. thanks now putting it together will be challenge for me. 555 timers available in stores like radio shack?

 

[Reloadron]

Actually the old 555 is readily available it Radio Shack as well as common resistors and capacitors. Remember the 555 circuit I posted was designed to work with my earlier link to handle the 120 VAC.

Ron

 

[oreoweb6]

ok. so do I need and old 555 timer or new one? also which is the inputs on your diagram?

 

[Reloadron]

Any standard 555 timer like this one available from Radio Shack. The circuit I provided has no input. When power is applied it has 2 outputs that are times as you mentioned and they toggle. Each output in the drawing would connect to the circuit I linked to earlier.

Ron

 

[oreoweb6]

here is wiring set up. Can you translate the set up from the new timer to this format please.

 

[oreoweb6]

the old timing circuit is in the picture with with wiring diagram

 

[Reloadron]

Uh oh, not what I expected. The board looks to take mains voltage and rectify it. Then feed some form of timer design. My initial take was there was a center light that was on for X time. When it went off the outer lights came on for X time. They alternated so neither the center or outer lights were ever on at the same time. Now, looking at the picture, I am not sure how they did it. I don't see what looks like any relay in the image, The 4 diodes I think rectify line voltage seem pretty apparent. I am just not sure what you have there. The board does not look to be complex I am just not sure how things are configured to have it do what it does.

Ron

 

[oreoweb6]

Thats why I mapped the wiring. something sounded different. The timer itself is very small on the circuit board. Will knowing the exact makeup of the diodes and capicitors help in a solution or is the unknown timer a wrinkle.

 

[dougy83]

It looks like the timer is a bridge rectifier and I'll assume a relaxation oscillator driving a switch across the rectified voltage (somewhat similar to the attached sketch).

If you can get a better picture of the top and bottom of the PCB, it should be easy to draw a schematic from it and given the values of the parts, it should be easy to suggest which ones are most likely to fail. If you have a multimeter you can test each part and replace ones that aren't up to

 

[4pyros]

Yes we need better pictures of the board top and bottom.

 

[oreoweb6]

I tried to get better pics but its hard. i will have to draw up the board. its will take some time for me. I have problems that limit me. i got some specifics on the parts. it seems both circuit boards share jacko 47uf 25v capicitor (yellow dot), brown diodes (puple x) 1)silver-red-red-gold 2)brown-red-yellow-gold 3)brown-black-red-gold)

the only differences: (green dot) bt1690 ph95-bad circuit and bt1690 ph90-good circuit.
silver and black diodes (red) in4007 MIC-bad circuit and in4007 WTE-good circuit.

there seems to be a smaller diode that is orangish color that is shared but its black from the one diode that smoked nearby. small diode looks like clear glass over it and has black line over c24 (maybe pt after it. very small to see). hope this helps for now

 

[4pyros]

the only differences: (green dot) bt1690 ph95-bad circuit and bt1690 ph90-good circuit.

They should be "BT169" a logic level thyristor. The rest of the digits are manufacturing codes like the lot and date. It is the part that switchs the voltage on and off and may be the dad part on your timer.