Hello
I have made a Clock with 4" 7seg display (comman Anode) which displays time,date,day of week, inside temp, outside temp and humidity with TSOP IR to set clock alarm etc.
Now I need to interface with an Alarm circuit ( attached ) to the arduino. Since I will be using a 12v power supply for Arduino, the 7 Seg display and the alarm circuit using UM66.
I am confused where to connect the input to alarm circuit from the arduino to trigger the alarm and the 12v rail to the alarm circuit. Just connecting a buzzer works fine as an alarm.
Thanks for your help.
Regards
Video : - YouTube
Do you mean make the Arduino press that button on the attached circuit?
If so then you need a PNP transistor, emitter to the 12V and collector to the UM66 melody generator. The the base needs to be connected to a 10K resistor to the 12V. Now in order to turn this transistor on the Arduino needs to pull the base low, but it needs to do this through an NPN transistor. Connect another 10K to the base of the first and connect the other end of it to the collector of the NPN transistor. Connect its emitter to ground and the base to the Arduino through another 10K resistor.
Thanks. Quite understand your point and will try this out as well.
Do you mean make the Arduino press that button on the attached circuit?
Ans: No push buttons etc. Its just going play UM66 on a pre determined Alarm time set. Since my circuit needs higher current I am working on something where I can directly derive from the Arduino itself. Instead of the BD140 hoping to use a BC547 and directly hooking up with one of the digital pins.
Thanks for your time, and will revert back on how it goes.
Did you get to see the video ? Attached my script for the clock..anything you think i need to tinker !! THX
Ans: No push buttons etc. Its just going play UM66 on a pre determined Alarm time set.
Yes but the push button doesn't have to actually be in place you are just powering your melody chip on a signal from the Arduino.
Rather than try and push more current through the speaker, which looks like 622mA with that circuit, try and mount the speaker in a better way. That has a much bigger effect on the volume you get.
Did you get to see the video
Yes but in terms of your problem it doesn't bring much to the party.
Thank you very much. I tried it with a BC547 replacing the BD140 on the output ( speaker end ) and very happy with the result. Was able to drive the melody chip right out of Arduino Digital pin 9. Just audible enough for an alarm.
I am using the the USB to power up my Arduino and external power supply (9 volt ) to the sound chip by circuit attached. Though connecting the 5 volt supply from the Arduino works fine, when i connect the 9 volt supply to the sound board i only hear " short beeps " and the melody did not play.
