Modifying Halloween Prop Circuit Board

Thread Starter

Raizieldragon

Joined Oct 20, 2020
8
I have a halloween prop that is a flickering light that is sound activated. When activated, the light comes on and flickers for a few seconds, then the cycle ends. There’s also a sound that can be turned on but I’m not using it. I’m trying to modify it so that the flickering light is always on (but still flickering) instead of needing to be triggered by sound.
I tried shorting the sound sensor, and it will initially trigger the flicker cycle, but if kept shorted it won’t re-trigger the cycle. It’s like it has a circuit built in that needs to see the input change.

the red is the positive from the battery, black next to it is the negative. Large black and white bundles on the right go to the lights. Two white wires on the left go to a “tester” that I could easily short out (but it has the same effect as shorting the sensor). Green wires go to the speaker (one is cut so the speaker won’t work). Yellow ones go to the sound sensor.

any assistance is greatly appreciated.
 

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sghioto

Joined Dec 31, 2017
1,556
You might be able to connect one of the yellow wires through a resistor to the red battery wire. A better photo would be helpful along with the sound sensor.
 

MisterBill2

Joined Jan 23, 2018
7,306
From the out-of-focus photo it appears that the brains of the device are all in a "chip on board" under that blob of black epoxy. The two transistors may power the lights or amplify the sound to the speaker. It seems that the two white wires connect to traces that go into that black blob. So what you need is an external component that connects the two white wires when ever the speaker goes silent. One way to do that will be a means to sense the modules current draw and connect the two trigger wires whenever the module stops drawing current. So if you have a multimeter you should measure the current drawn by the module when it is silent and when it is making sound. That will allow a determination as to how to continue the project.
 

Thread Starter

Raizieldragon

Joined Oct 20, 2020
8
You might be able to connect one of the yellow wires through a resistor to the red battery wire. A better photo would be helpful along with the sound sensor.
The yellow wires go to the sensor. Nothing would happen if I connect the sensor directly to the power from the red wire.
 

Thread Starter

Raizieldragon

Joined Oct 20, 2020
8
From the out-of-focus photo it appears that the brains of the device are all in a "chip on board" under that blob of black epoxy. The two transistors may power the lights or amplify the sound to the speaker. It seems that the two white wires connect to traces that go into that black blob. So what you need is an external component that connects the two white wires when ever the speaker goes silent. One way to do that will be a means to sense the modules current draw and connect the two trigger wires whenever the module stops drawing current. So if you have a multimeter you should measure the current drawn by the module when it is silent and when it is making sound. That will allow a determination as to how to continue the project.
The white wires go to two prongs that were connected to a tester/demo button that is no longer attached. Shorting them does trigger the cycle, but keeping them shorted doesn’t repeat the cycle.

also, I’m not using the speaker at all.
What I want to do is figure out where I can connect the power so that the flicker circuit is just always under power when the switch is on. I don’t want to have to build a complicated “detect and trigger” circuit when I just need an always on circuit to replace the sound trigger circuit.
 

Thread Starter

Raizieldragon

Joined Oct 20, 2020
8
Sorry about the wires in the way. The components are: 2x J3Y transistors on the left; in the middle, from top to bottom are a resistor, another resistor, then a capacitor. There’s another capacitor to the right, between the black and red power wires. Then far top right corner, there is something that’s just labeled with a big O. I think it’s an OR gate. If you need photos of specific sections, let me know and I can try to get better shots of other areas. It’s a little hard to hold the camera, and get the wires out of the way at the same time.
 

sghioto

Joined Dec 31, 2017
1,556
I don’t want to have to build a complicated “detect and trigger” circuit
Might be the only way. The mic element along with other components is creating a sound activated switch going to the micro. The micro senses this switch (either a high or a low) and triggers the lights but like you said must see a change in the switch before reactivating.
 

Thread Starter

Raizieldragon

Joined Oct 20, 2020
8
Might be the only way. The mic element along with other components is creating a sound activated switch going to the micro. The micro senses this switch (either a high or a low) and triggers the lights but like you said must see a change in the switch before reactivating.
I am hoping there is a way to connect/short the power around the micro. So if the micro controls the power in and decides when to send it out to the flicker circuit, I should be able to jump the power in to the power out of the micro, circumventing the micros detection circuit.
 

MisterBill2

Joined Jan 23, 2018
7,306
What I suggested was an arrangement to deliver a momentary trigger to restart the system every time it stops. That would be flickering lights or making sounds, the scheme is to generate a new trigger every time it switches off, and then remove that trigger as soon as it switches back on. A current sensing relay in a battery power leak could do just exactly that, which is why I suggested that the TS must measure the current drawn in the on mode.
 

sghioto

Joined Dec 31, 2017
1,556
Might be a way to connect a low current SPDT relay using the NC contacts. When power is turned on the closed contact wired across the the test switch will activate the lights, relay pulls in and contact opens. Lights go off, relay drops out reactivating the lights.EEE razieldragon halloween mod.png
 
Last edited:

djsfantasi

Joined Apr 11, 2010
6,962
I am hoping there is a way to connect/short the power around the micro. So if the micro controls the power in and decides when to send it out to the flicker circuit, I should be able to jump the power in to the power out of the micro, circumventing the micros detection circuit.
I doubt you could bypass the micro. I suspect that it also contains the flicker “circuit”. Software in the blob creates the flicker effect. I don’t see in your photos, any evidence of a separate flicker circuit.

This leaves repeatedly activating the circuit. I’d experiment with a 555 circuit which sends a pulse that occurs after waiting for the cycle length.
 

MisterBill2

Joined Jan 23, 2018
7,306
Might be a way to connect a low current SPDT relay using the NC contacts. When power is turned on the closed contact wired across the the test switch will activate the lights, relay pulls in and contact opens. Lights go off, relay drops out reactivating the lights.View attachment 220146
This circuit is a bit more complex than my idea but it would work in a similar manner, of generating that start signal when the lights went out. so it would work as well.
 

Thread Starter

Raizieldragon

Joined Oct 20, 2020
8
Thanks all. I don’t know what most of the components/circuits you’re suggesting are. It’s been over a decade since I took my circuits class with no practice or actual experience. Also don’t have any of the components you’re suggesting using either, so couldn’t build it even if I knew how.

i was hoping some of those external components were the flicker circuit; specifically one of the capacitors. If not, I’ll probably just put it back together the way it was.

thanks again.
 

Dodgydave

Joined Jun 22, 2012
9,666
Thanks all. I don’t know what most of the components/circuits you’re suggesting are. It’s been over a decade since I took my circuits class with no practice or actual experience. Also don’t have any of the components you’re suggesting using either, so couldn’t build it even if I knew how.

i was hoping some of those external components were the flicker circuit; specifically one of the capacitors. If not, I’ll probably just put it back together the way it was.

thanks again.

If you want to keep the badge or container, just replace the LEDs with flashing ones, and wire them to a battery.
 

djsfantasi

Joined Apr 11, 2010
6,962
Are you familiar with coding?

An Arduino Nano out of the box could be programmed to repeat a start pulse continuously, and pause until the next time you need to “press the start button”.

It’s painfully simple IF you can code. The Nano is under $20 and comes with an USB programming cable. Plus, the software needed to write your code and upload it to the Nano is free.

In fact, the whole thing can be done with the Nano. Turn the flickering LEDs on and off, be triggered by sensors and flicker the LEDs.

I made a birthday cake with six flickering candles with a Nano. Look at this article. The code is there, too.
 
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