Hello guys,
I am trying to build a circuit that seamed simple at first (and I am pretty sure it is) but my very basic knowledge in electronics betrayed me midway. Any help will be greatly appreciated!
Here it is:
I have a AC monitor which among other functions also has an alarm for exceeding an adjustable power threshold. When too much power is drawn it flashes the LCD screen backlight. That is alright but I wanted to add an audible alarm to it as well, so on the monitor's board I found the alarm output pin on the IC, which is oscillating 3VDC at 2Hz. I also located the output of an LM7812 at the very beginning of the circuit, so I thought, lets hook up a 12 volt buzzer with a PNP and bias it from the oscillating alarm output. It worked nicely but...
I want the alarm to buzz at a threshold lower than the absolute max possible, which means that sometimes the alarm buzzes while I still have some margin, which is irritating. I would like to add a silence/acknowledge momentary switch, which will mute the buzzer until the alarm is off and re-triggered by the monitor's circuitry (or even better if it is not too complicated, for 5-10 minutes). And that's where I am stuck.
Thank you in advance,
Pete
I am trying to build a circuit that seamed simple at first (and I am pretty sure it is) but my very basic knowledge in electronics betrayed me midway. Any help will be greatly appreciated!
Here it is:
I have a AC monitor which among other functions also has an alarm for exceeding an adjustable power threshold. When too much power is drawn it flashes the LCD screen backlight. That is alright but I wanted to add an audible alarm to it as well, so on the monitor's board I found the alarm output pin on the IC, which is oscillating 3VDC at 2Hz. I also located the output of an LM7812 at the very beginning of the circuit, so I thought, lets hook up a 12 volt buzzer with a PNP and bias it from the oscillating alarm output. It worked nicely but...
I want the alarm to buzz at a threshold lower than the absolute max possible, which means that sometimes the alarm buzzes while I still have some margin, which is irritating. I would like to add a silence/acknowledge momentary switch, which will mute the buzzer until the alarm is off and re-triggered by the monitor's circuitry (or even better if it is not too complicated, for 5-10 minutes). And that's where I am stuck.
Thank you in advance,
Pete