Hi,
Within my model project I have this machine gun circuit installed and separately a voice recorder module. They are in different parts of my project but share the same battery power supply.
Everything is working as required but as I release the button for the MG the VR playback is triggered in error.
The MG circuit speaker is replaced with a 10 ohm resistor and the output is then amplified by a TDA2030 module which also amplifies the VR output but isolated by 0.47uf cap.
The MG circuit drives a 5v relay and I have a 1N4007 diode to stop flyback.
The VR’s playback button is extended and close to the MG’s control button.
I don’t have the circuit for the VR just a picture.
How can I suppress this from happening?

 

What have you tried already to solve the problem?

From your description you have probably created an antenna connected to the VR trigger.

If that is the problem, then maybe placing a filter at the pin could solve the issue.

 

What have you tried already to solve the problem?

From your description you have probably created an antenna connected to the VR trigger.

If that is the problem, then maybe placing a filter at the pin could solve the issue.

Thank you for your thoughts.
I have thought along the line of inducing a spike and I have screened and twisted the wires to the VR button.
A spike/surge protector filter may be the answer but I’m not sure of the best setup or circuits. Any suggestions would be much appreciated.
Peter

 

Where is the button switch and relay configured in the 555 circuit.
Why is there a 10uf cap from pin2 of the speaker to the base of the BC557?

 

Where is the button switch and relay configured in the 555 circuit.
Why is there a 10uf cap from pin2 of the speaker to the base of the BC557?

Hi, thanks again for replying.
MG button controls the relay which switches on the power to MG circuit.
Not being an expert on circuitry I know that the speaker is part of and a requirement for the circuit as, I guess, the 10uf cap.
Peter

 

Where is the button switch and relay configured in the 555 circuit.
Why is there a 10uf cap from pin2 of the speaker to the base of the BC557?

Sorry, the relay isn’t driven by the MG circuit it switches it on and off, sorry.

 

I suggest a capacitor directly across the DC power terminals of the circuit you show u in post #1. At least 100 Mfd, rated at least ten volts, 15 or20 volts rating will be reasonable. And it does need to be connected close to that circuit.

 

Hi, thanks again for replying.

Where is the Vr playback button connected on the module?
What is the battery voltage both circuits share?
Why are you using a relay to switch on the MG circuit? It draws only a few miiliamps of current.
Seems the whole project might be powered differently to avoid your issue.

 

Where is the Vr playback button connected on the module?
What is the battery voltage both circuits share?
Why are you using a relay to switch on the MG circuit? It draws only a few miiliamps of current.
Seems the whole project might be powered differently to avoid your issue.

Thank you again for your comments.
Yes, I’ve had a thought about the power setup and probably have a solution.
The relay is used to also control two electro magnetics, again with flyback protection, so is needed. As there are 10 sections to my model's functions I hadn’t considered this idea. I’ll now take the VR supply from the NC side of the MG relay so MG on VR off.
I’ll try this later and hopefully the milliseconds between off and on will be enough to stop the VR triggering.
Peter

 

I suggest a capacitor directly across the DC power terminals of the circuit you show u in post #1. At least 100 Mfd, rated at least ten volts, 15 or20 volts rating will be reasonable. And it does need to be connected close to that circuit.

Thank you for your suggestions. As I’ve written below, I may have a simple solution but this might still require your cap setup.
I’ll let you know how I get on.
Peter.

 

Thank you for your suggestions. As I’ve written below, I may have a simple solution but this might still require your cap setup.
I’ll let you know how I get on.
Peter.

Hi,
Well my thought of powering from the NC of the MG relay didn’t change anything. Also tried the 100mfd but no luck.
I’m now considering a 555 timer to delay the VR turning on as a few milliseconds wasn’t enough.
Again I’ll let you know what works.
Peter

 

This transistor circuit might work as well.

Another version:

 

This transistor circuit might work as well.
View attachment 335798

That looks good, thank you, I’ll try it.
Peter

This transistor circuit might work as well.
View attachment 335798
Another version:
View attachment 335801

 

Thank you again for interesting options.
As I’m very restricted on space I’ll go with the single transistor circuit. I’m assuming that the capacitor value will determine the length of delay so I can vary that until the triggering stops.
Peter

 

Correct.
What is the voltage supply for the VR module?
There is an appx 0.7 volt loss through the transistor is why I'm asking.

 

Thank you all for giving me some very helpful comments
I’m pleased to report that the triggering problem has now been resolved.
I did try your circuits Sghioto but sadly with no success. I won’t go into any technical reasoning but firstly the triggering remained, so probably not delayed enough secondly strangely, the playback track was slowed down to a muttering drivel and thirdly it required an additional way to discharge the capacitor.
Anyway, I made the attached 555 circuit (sorry, with a 100uf Cap not 1000) together with a SSR which is small and gives a seven second delay - enough to stop triggering the VR.
Thank you again for your support and time.
Peter.