Current Activated Buzzer Circuit Advise
Current Activated Buzzer Circuit Advise
(OP)
I'm trying to have a buzzer beep when current is applied to a transformer, spec sheet attached. I have an idea of what I would do I just want to run it by you guys and see what you think
I was thinking of using one of these current sensors
http://s earch.digi key.com/sc ripts/dkse arch/dksus .dll?pname &site= us;lang=en &wt.mc _id=Dxn_US _T091_Catl ink;name=3 98-1000-ND
and run the output wire through it and use the output of that to run this circuit to make the buzzer beep.
http://www.doctronics.co.uk/555.htm#pb_04
for my buzzer circuit i used an NPN transistor and a 5v buzzer and that works fine when a voltage of 2.5V or greater is applied, I'm just not sure how to trigger it.
Do you think this would work, the output of the transducer is high voltage, high frequency >20khz
Ok I measured the output of the transducer using this current probe
http://www.aemc.com/products/pdf/1201.51.pdf
here is what i got with the probe set to 100mA/V
Cyc RMS = 472mV
Rise Time = 14.84us
Fall Time = 18.20us
Pos Width = 24.7us
Neg Width = 24.20us
Freq = 20.45kHz
Period = 48.90us
Mean = 68.7mV
Pk-Pk = 1.54V
so from those measurements I am seeing that I would probably need to measure current up to 154mA?
i'm kinda stumped here, i'm trying not to mess with the original circuit if at all possible, what is the easiest way to detect output from the transformer and have that output a voltage signal of at least 2.5V
I have the buzzer circuit working with a 555 timer and a npn transistor but i'm not sure how to only activate it when there is output from the transformer
any help would be greatly appreciated thanks.
attached is the transformers spec sheet
I was thinking of using one of these current sensors
http://s
and run the output wire through it and use the output of that to run this circuit to make the buzzer beep.
http://www.doctronics.co.uk/555.htm#pb_04
for my buzzer circuit i used an NPN transistor and a 5v buzzer and that works fine when a voltage of 2.5V or greater is applied, I'm just not sure how to trigger it.
Do you think this would work, the output of the transducer is high voltage, high frequency >20khz
Ok I measured the output of the transducer using this current probe
http://www.aemc.com/products/pdf/1201.51.pdf
here is what i got with the probe set to 100mA/V
Cyc RMS = 472mV
Rise Time = 14.84us
Fall Time = 18.20us
Pos Width = 24.7us
Neg Width = 24.20us
Freq = 20.45kHz
Period = 48.90us
Mean = 68.7mV
Pk-Pk = 1.54V
so from those measurements I am seeing that I would probably need to measure current up to 154mA?
i'm kinda stumped here, i'm trying not to mess with the original circuit if at all possible, what is the easiest way to detect output from the transformer and have that output a voltage signal of at least 2.5V
I have the buzzer circuit working with a 555 timer and a npn transistor but i'm not sure how to only activate it when there is output from the transformer
any help would be greatly appreciated thanks.
attached is the transformers spec sheet





RE: Current Activated Buzzer Circuit Advise
If the voltage is higher than about 2.5V you can use a FET as a switch to power up your entire 555 buzzer circuit.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Current Activated Buzzer Circuit Advise
i have attached the picture of what i have to work with, some how i need to detect when there is output from the transformer
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
Use a voltage comparator to trip at a variable voltage, you can set with a resistor value, or with a pot, to run a FET to turn on your 555 circuit.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
thanks
RE: Current Activated Buzzer Circuit Advise
http://ww
RE: Current Activated Buzzer Circuit Advise
i have attached the picture of what i have to work with, some how i need to detect when there is output from the transformer"
Why not simply hook up a buzzer with rated voltage on secondary of xformer? The transformer is not high frequency is it?
http:/
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
The trail of thought you have is for sure a more interesting way to proceed, LPS for that.
Thanks
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
http
John D
RE: Current Activated Buzzer Circuit Advise
anyone have any ideas, thanks
RE: Current Activated Buzzer Circuit Advise
Could the problem be the sound transducer is a piezo? That would give really low output. Put a 470 ohm resistor across it and see of you get sound then. We (not my design) were driving these with two gates to get about 20V PP and a pot to adjust to resonance. These were driven so hard that they were failing in the field. Got out my microscope and the wires were cracking from fatigue.
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
h
Cheers,
G
RE: Current Activated Buzzer Circuit Advise
anyways here is another picture of something i'm trying
i'm using a bridge rectifier to convert the ac to dc. when i measure the output voltage from the rectifier i'm getting over 100V but if i add a LED the voltage drops down to below 1V and the LED doesn't stay lit it flickers
any ideas??
RE: Current Activated Buzzer Circuit Advise
However that was just a test to see if it would work, now I need to figure out how to power the op amp with just a single supply of either 5V, 14V, or 24V. I tried using the 24V supply and using a voltage divider to create a virtual ground but when I do that I get -21V, and like 2.5V which is strange, schematic below
RE: Current Activated Buzzer Circuit Advise
A second approach is to use two 9V regulators (you need to leave some overhead for the regulators to work); this will still be a bit tricky though.
John D
RE: Current Activated Buzzer Circuit Advise
here is the output of both the current sensor and of the opamp i just can seem to get enough output to turn on the transistor any ideas
CH2 = Output of current sensor input to opamp
CH3 = output of opamp
the current sensor i'm using is CSI-0100
http://ww
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Current Activated Buzzer Circuit Advise
thanks
RE: Current Activated Buzzer Circuit Advise
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Current Activated Buzzer Circuit Advise
I suggest the following attached circuit using an open collector LM339 op amp. D1 provides a reference voltage of .6 volt. Above that, the open collector of A1 discharges the 1uF cap. 2.2K resistor can be inserted if a random pulse is a problem. The second comparator is made from the remaining three op amps to provide generous current sinking. Switching at 1/3 supply voltage provides some time delay. Reversing the two resistors could provide a better delay.
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
RE: Current Activated Buzzer Circuit Advise
on your drawing, which inputs are the inverting and non-inverting inputs of the op amps
thanks
RE: Current Activated Buzzer Circuit Advise
You have a nice current probe.
Certainly not a cheap scope.
A cad system.
And you are likely getting paid for this.
I'm sitting in a cabin in the woods with no electric.
The omission of the input polarities was on purpose. You said you were familiar with analog design. This is a good circuit with minimal components. This is Engineering Tips. I've given you a direction and you just need to fine tune the threshold and lengthen the time constant.
RE: Current Activated Buzzer Circuit Advise
See my previous comment...
Dan - Owner

http://www.Hi-TecDesigns.com