How to connect a flashlight to an alarm clock??

I want to replace the buzzing noise with light from a flashlight. something easy?

Hi,
Definitely you can use flash lights instead of Buzzer. For that you have to check the voltage range. Practically 5V, 9V , 12V , etc buzzer types are available. You cant connect flashing light circuit directly there. Care about your flashing circuit voltage requirements.....


Regards

Sudan

Hi thanks a lot for replying. The flashlight I want to connect is a little one like these: https://www.maglite.com/ but cheaper. I just kind of imagined I'd use a diode or a transistor maybe?, remove the buzzer, then connect the diode and the flashlight?
But I know nothing of electronics =(
I could try to read a book but I need some orientation first =) and to know if my idea is possible too.

Its definitely possible.

But there area few very little things to be understood.

you have to identify certain points.

1.If you have a multimeter measure what voltage it comes across the buzzer pins when it is energised.

2.Now,next you have to know what is the voltage to be given to the flash light for it to glow.

now understand these things. Both the voltages may be different.
Even if both the voltage level are same, you cannot just replace the buzzer with the flash light because the clock circuitry will not be able to supply enough current for the flash light, whereas it will be designed only to supply the low current required for the buzzer.

So this will be the scenario.

If the above said are correct, then you need to find an alternate solution for that.

And the simplest method is to use a transistor and a small relay so that the flash light can power on with its own separate battery and need not drain the clock battery.

If you are clear with this, will proceed.

Regards,

Oh thanks a lot =)
I like that simpler method with the relay and the transistor. I like that the flashlight uses its own batteries.

yes I'm clear with that and ready to proceed

well,

now you need to have these things ready,

1. A General Purpose soldering board and materials for soldering like soldering iron ,lead or any alternate arrangement where you can carry out these.

Components:-
2. Transistor - BC547 or equivalent
3. Resistor - 1/4 Watt - 1K
4. Diode - 1N4007
5. Relay - SPST ( With just 1 NC Contact )
Coil Voltage - 5VDC (A small Relay)

Now, Look at the circuit attached.And wire the components on the general Purpose board as shown in the circuit.

A Very small amount of basic knowledge in electronics is mandatory.

Get back if you have any doubts, and definitely you will have it.




what is the clock battery voltage.If it is not or more than 5V, then there has to be a slight modification in deriving the coil voltage for the relay.But basically ,the circuit remains the same.

That circuit may not work. In the battery alarm clocks I've played with, the buzzer's (+) goes to the battery (+). The buzzer's (-) goes to an open collector NPN transistor or N-MOSFET. You would need a PNP transistor ahead of your NPN. Emitter to battery (+), base resistor (100K) to buzzers (-), and collector to a load resistor (10K) to battery (-). Your R1 to the PNP's collector.

Ken

KMoffett said:

You would need a PNP transistor ahead of your NPN. Emitter to battery (+), base resistor (100K) to buzzers (-), and collector to a load resistor (10K) to battery (-). Your R1 to the PNP's collector.

Ken

Click to expand...

please clarify,with a circuit diagram if possible.

KMoffett said:

That circuit may not work. In the battery alarm clocks I've played with, the buzzer's (+) goes to the battery (+). The buzzer's (-) goes to an open collector NPN transistor or N-MOSFET.
Ken

Click to expand...

That is why i told to check what is it happening when the buzzer is energised.

If as you said, its already an open collector scenario, then you wouldnt need any drivers outside as well. cant you make use of the same open collector to drive the coil. ? just a clarification.

Before I post a schematic:
What's the voltage of the clock...1.5V?...3V?
What 's the voltage of the light?...1.5V?...3V?...4.5V?
What's the current draw of the light?

The buzzers I've encountered in clocks are not self-contained buzzers, but piezo elements that are pulsed by the clock circuit.

1. The open collector output is meant to drive a very small load (piezo element) and could not drive a light directly.
2. The output circuit would try to pulse the lamp at the alarms high frequency, and the lamp may not respond fast enough to light.

Ken

Those details of the voltages will be very much useful to go any further.
looking forward for that.

KMoffett said:

1. The open collector output is meant to drive a very small load (piezo element) and could not drive a light directly.

Ken

Click to expand...

Yeah, I dont want to remove the relay part.That should be still there.
The coil of that relay can be directly driven by that clock open collector instead of that external transistor is what i meant.Still I am not sure of the capability of that open collector.

Since most battery clocks use either one or two AA batteries, even if the clock output could handle the relay coil current (doubtful), where are you going to find to relays with 1.5V or 3V coils?

Ken

KMoffett said:

where are you going to find to relays with 1.5V or 3V coils?

Click to expand...

kindly read the post carefully.I've already commented on that previously.

cameo_2007 said:

"what is the clock battery voltage.If it is not or more than 5V, then there has to be a slight modification in deriving the coil voltage for the relay."

Click to expand...

I was a little busy so I haven't got a multimeter yet. I'm gonna borrow my brother's in a couple days.

What you all have posted so far is great, thanks

This is what I had in mind.

Ken