Monostable using NE555 is used to play a UM66 IC: battery drains rapidly

[bimalkamal]

In the given circuit a monostable using NE555 is used to play a UM66 IC for about 11 Sec. The circuit is working Ok but the problem is, it is consuming enormous power. My friend using this as a calling bell for his ill mother. According to his report the bell needs a new 9V battery pack every alternate day. Any solution? The speaker is of 8 ohms 2.5 inch diameter.

I cant access the circuit immediately as my friend lives far away. Only I can do is to make another model and send it to him.

My requitement is this -> only one push and the bell should play for about 10 sec. (low consumption)

 

[sky_123]

I've not used a 555 for a long time, but I think NE555 uses a few mA of power, i.e. enough to drain a small 9V battery in a few days. In your circuit, the NE555 is powered up always. You do need a different circuit, maybe use a MOSFET to supply power to the circuit for >10sec when the switch is pressed (e.g. charge a capacitor when the switch is pressed, which then discharges through a resistance, leaving >10 sec for the mosfet to stay turned on, i.e. enough time for your NE555 to produce the controlled duration.

 

[erikl]

Or use the CMOS version of the 555 timer, e.g. LMC555. At Vb=9V it has a typ. quiescent current consumption of 130µA instead of the ≈5mA of the NE555 .

 

[bimalkamal]

Or use the CMOS version of the 555 timer, e.g. LMC555. At Vb=9V it has a typ. quiescent current consumption of 130µA instead of the ≈5mA of the NE555 .

This sounds good. I will try this.

---------- Post added at 22:23 ---------- Previous post was at 22:11 ----------

charge a capacitor when the switch is pressed, which then discharges through a resistance, leaving >10 sec for the mosfet to stay turned on, i.e. enough time for your NE555 to produce the controlled duration.

Any suggested circuit? I have tried this. But in my case, as the charge of the capacitor decreases, the connected transistor's (acting as a switch) base bias voltage also getting changed. As a result, the music starting fine but after few seconds before stopping there is a decreasing distorting sound. Any modification is there so that after a few seconds the base bias voltage to the transistor will go suddenly to 0?

 

[dselec]

I dont get it . does the um change tune every time it gets supply from the 555 for several seconds ?

 

[bimalkamal]

No. That was in response to sky_123's suggestion. see post #2 above

 

[sky_123]

I think the attached cct would work (I've not tried it). You can see where it attaches with reference to the existing R2 and S1.
Basically you'd need a p-channel enhancement MOSFET, e.g. BSS84.
If the cct doesn't work, then stick the top end of the R2 resistor directly to the 9V supply rather than the
switched supply (I don't know if the 555 will trigger otherwise). The cct should supply power for longer than 10 sec,
i.e. long enough for your 555 circuit to do its thing.

 

[bimalkamal]

Thank you Mr. Sky_123. I will try it and let you know.