Electronics help- Hallmark!

[Prince of Styrene II]

Okay, so here's where my limit of electronics comes to an end. Actually it ended long ago, but let's not quibble, okay? I bought one of those musical Hallmark cards that when you open the card, it plays a song, movie quote or whatever. Since I'm still in the process of building "King" from the movie Cars, when I found a Cars card that had a reving sound chip in it, I couldn't pass it up! Now here's the description & problem:

When you close the card, a plastic tab slides into place, preventing the circuit from being complete. When the card is open, there's a small hole in the plastic tab that let's the circuit connect. When the card is left open, the chip plays for about 15 seconds & then automatically shuts off. Close the card, open it back up & the chip plays again.

I thought I could get a "click on, click off" switch & connect it within the wires to have an on/off switch. Problem is that when the 15 seconds runs out it won't play again, even when the switch is turned off & on again.

Somehow I need to remove that "timer" & have the chip play when the switch is pressed. Here's a big image of the circuit board. Does anyone have the knowledge to tell me what I need to do?
http://planetmyhill.com/Modelmaster/PIC ... ircuit.jpg

The speaker is the circular brass thing on the right. You can see the plastic tab (with the square hole) above the battery under the "spring" that connects the circuit when the card opens. The white wire going off the top of the picture was connected to where the bare wire is, but I used the bare wire to lengthen for the switch.

Does anyone have any ideas? This sound chip is just too good of an opportunity to pass up!

[DennisH]

I'm no expert on this kind of stuff, but it looks like you disconnected the speaker wire and ran the switch off of that?

I'd reconnect the speaker wire to the spot where it was and then wire the switch to the "spring" and its counterpart connection to complete the on/off curcuit.

I think.


Dennis

[Prince of Styrene II]

I'm no expert on this kind of stuff, but it looks like you disconnected the speaker wire and ran the switch off of that?

Yep.

I'd reconnect the speaker wire to the spot where it was and then wire the switch to the "spring" and its counterpart connection to complete the on/off curcuit.

I think.

It's as good an idea if any. I'll try it. Does anyone else have another idea.

[Prince of Styrene II]

Okay, I've been posting this on other boards because I wanted to get as many minds on this as possible. Turns out that the wife gave me the base idea for the solution! All this time I wanted to make King's gas cap the on/off switch. But then when I actually stuck the switch through the hole, I realized that I'd need about a 1/4" actaully sticking out of the hole to be able to push it in to trigger it!

Here's what I ended up with. I'm going to put the spring side of the circuit mounted near the inside of the gas cap. The spring will be raised slightly, breaking the circuit with no plastic tab. When something (oh, say a gas can nozzle!) is inserted into the hole, it will complete the circuit & start the sound! Here's a pic of the idea, using my pin vice as the gas can.

http://planetmyhill.com/Modelmaster/PIC ... it3_sm.jpg

What'cha think?

[DennisH]

So simple and so freakin sweet! That'll be an awesome display! Did you give her a hug?

Very cool, indeed .


Dennis

[Prince of Styrene II]

So simple and so freakin sweet! That'll be an awesome display! Did you give her a hug?

Very cool, indeed .

Thanks! I think it'll be something fun to have on the shelf.

And I gave her much more than a hug last night! There was a kiss, too!

[DennisH]

What's really cool is that it looks like it fit right in, almost like it was made fot it.

Did you have to mod it to fit or did it just fall into place?


Dennis

[Prince of Styrene II]

What's really cool is that it looks like it fit right in, almost like it was made fot it. Did you have to mod it to fit or did it just fall into place?

The sound chip? No mods other than cutting the back of the greeting card down around the chip. The speaker ends up sitting nicely on the inside of the roof.

[DennisH]

Niiiiiiiiiiiice!

How is King coming along?


Dennis

[Prince of Styrene II]

Slow. I havn't had a chance to work on him for a couple days, though I did make some shocks for him which are visible because I have his left rear tire raised up a bit on the suspension, mimicking the beauty shot on the Cars website.

[Sparky]

I know you've got it figured out but I'd just like to review the speaker switch you tired originally.

It looked like two wires went to the one pad on the circuit board. Is this an illusion of the wire used? Any ways its unlikely that this would be doing the same thing that the plastic tabs in the card did:

First: the circuit to detect when a speaker load is not present (or shorted) is more complex than needed for this application, really its good for portable setups were someone might have missed attaching a speaker and you'd like the user to get a signal that a speaker is missing from network, or that a set of speaker lines are shorted out.

Second: If the card reset and played when it detected the speaker was re connected, that would mean it was on all the time, waiting to and testing to see if the speaker were connected. With such a small battery and the need for shelf life, there's not a good chance the circuit would even be considered.

So what the tabs are doing is simply this, they are disconnecting the battery, so that absolutely no load other than the batteries internal resistance leakage, is draining on it.

The simple answer is to remove the battery and route a regular 3 volt power source to it, somewhere that's easy to change or just plug into. and use a switch on the power line to reset/turn off and on the sound.

With circuits as small as this you can probably use the home security system magnetic reed switches. in this configuration you want a Normally Closed switch (N.C.). Then have a master cutoff switch somewhere else. When the sound clip needs to be re triggered, you swipe a magnet across some spot on the model or display base and the circuit is momentarily broken then closed so that the audio starts to replay. Re=member that the circuit will always be on drawing load on a battery, and if left like this for long periods of time you risk a battery leaking, that's why you need a master cutoff.

[Sparky]

I think you might have tried the speaker switch by trying to 'Ohm' out where the tab switch was connected. . .

Likely this is breaking one of the connections to the battery, if it is breaking the ground connection or the negative side of the battery this can be deceiving. If the circuit is setup so that one side of the speaker is connected to ground, then 'ohming' out the switch could deceive one into thinking that breaking the connection to the speaker does the same thing as breaking the connection at the same place as the metal tab. Only inspecting the traces on the circuit board might help to reveal what part of the circuit the metal tab switch is really interrupting. And only if the circuit board is a simple 2 sided board. (Those power planes sandwiched in some more complex circuit boards are really tricky.)

In this case you really need to break the connection to the battery to allow the circuit to reset, the timer is configured in one shot mode.

[Prince of Styrene II]

Sparky, it looks like you gave this problem some serious thought. Thank you! But most of what you said went right over my head! I think I'll just stick with my gas can idea.

[Sparky]

The moral of the story is that the metal part that the card tabs make & break to form a switching action, is the connection to the battery. And most devices will work this way

[Prince of Styrene II]

The moral of the story is that the metal part that the card tabs make & break to form a switching action, is the connection to the battery. And most devices will work this way

Ah, okay. I understand it a bit better now. Thanks!