Hey there,



I have created a circuit for a torch using quantum tunneling composite (QTC) as the switching mechanism while using a thyristor as a latch switch.




QTC is a smart material that is normally a perfect insulator but as you apply pressure it becomes a conductor.




http://s18.postimage.org/3vdwz0ck9/SAM_0093.jpg
This is the circuit.




its powered by a 12V 23mA n type battery and the circuit all works fine, it switches on and off no worries.




The issue is when the circuit is not used the battery gets really really hot and burns out with in a very short amount of time, the torch itself can be lit for over 26 hours.




I can only think the battery is being shorted but I cannot see where, unless the thyristor is allowing current to flow through striaght to the battery.




Can anyone spot the problem and help solve it?



Any help or suggestions would be greatly appreciated!



Thanks, Aron.

 

On the thyristor... what is the story on what looks like leftover solder or other possible shorts between the component lands ?

 

The soldering is fine on the thyristor, there is no bridging, the bridging on the LEDs in ok as its just the solder flowing along the track

 

Some more circuit images that can perhaps paint a better picture

http://s18.postimage.org/rsta92yl5/SAM_4383.jpg
http://s1.postimage.org/72v75pf1r/SAM_4382.jpg
http://s12.postimage.org/cb1ddqynh/SAM_4381.jpg
http://s12.postimage.org/8fxzb6fhp/SAM_4380.jpg

 

The issue is when the circuit is not used the battery gets really really hot and burns out with in a very short amount of time, the torch itself can be lit for over 26 hours.




I can only think the battery is being shorted but I cannot see where, unless the thyristor is allowing current to flow through striaght to the battery.

There is only one way a battery overheats and that is excessive current. I suspect the thyristor is not being turned off correctly or there is a current path through the parasitic diode.

Impossible to tell until you print the schematic you are using with component values.

 

I already made this mistake. The battery holder is cutting through the paint and shorting the battery. Put some black tape on the battery.

 

Sussed it!

the battery shell is conductive, so when the circuit wasn't in use the current was flowing from the batter clips through the battery shell, causing the short.

 

That's why you checked here...to find other people that make misteaks