Hello,
I am an absolute newbie trying to self learn. I have a commercial alarm clock based on the LM8560 IC. I need to get up at different time almost on different day of the week and I need to set the alarm every night before I go to bed. The problem is to set the time for the alarm, I would push and hold the 'hour' or the 'minute' button one at a time and they only advance forward, at a 2Hz rate. So if I need to change my alarm time from 7:45am to 6:30am, my finger will have to hold down the buttons a combined time of over 30s. The buttons are very stiff and hard on the finger too.
I opened it up and saw the circuit is very close to this reference circuit http://www.datasheetcatalog.org/datasheet/sanyo/LM8560B.pdf
Holding down Min-set(pin 21) or Hour-set (pin 22) will short the individual pins to Vss and the chip will automatically advance the respect digit at 2Hz. It doesn't look like the 2Hz rate can be made faster from outside the chip. However, I am thinking if I construct a switch using semi-conductors that will do the on-off switching on those time-set pins at 10-12Hz, it should serve my purpose.
I took some measurement using a multimeter as follow:
Vss to ground = 16.4V
Vss to pin 21 or pin 22 = 12.8V
short circuit current flowing from Vss to pin 21 or 22 = 6uA.
Initially I was thinking of using a 555 timer to supply the 10Hz Vcc to pin 21/22, but was not sure the "0" phase (ground) output of the 555 pulse will short the pin 21/22 to ground causing any damage to the ic.
Alternately can this be done with simple transistors-only circuits?
Any help or suggestion will be greatly appreciated.
Thanks!
Thank you.
I am an absolute newbie trying to self learn. I have a commercial alarm clock based on the LM8560 IC. I need to get up at different time almost on different day of the week and I need to set the alarm every night before I go to bed. The problem is to set the time for the alarm, I would push and hold the 'hour' or the 'minute' button one at a time and they only advance forward, at a 2Hz rate. So if I need to change my alarm time from 7:45am to 6:30am, my finger will have to hold down the buttons a combined time of over 30s. The buttons are very stiff and hard on the finger too.
I opened it up and saw the circuit is very close to this reference circuit http://www.datasheetcatalog.org/datasheet/sanyo/LM8560B.pdf
Holding down Min-set(pin 21) or Hour-set (pin 22) will short the individual pins to Vss and the chip will automatically advance the respect digit at 2Hz. It doesn't look like the 2Hz rate can be made faster from outside the chip. However, I am thinking if I construct a switch using semi-conductors that will do the on-off switching on those time-set pins at 10-12Hz, it should serve my purpose.
I took some measurement using a multimeter as follow:
Vss to ground = 16.4V
Vss to pin 21 or pin 22 = 12.8V
short circuit current flowing from Vss to pin 21 or 22 = 6uA.
Initially I was thinking of using a 555 timer to supply the 10Hz Vcc to pin 21/22, but was not sure the "0" phase (ground) output of the 555 pulse will short the pin 21/22 to ground causing any damage to the ic.
Alternately can this be done with simple transistors-only circuits?
Any help or suggestion will be greatly appreciated.
Thanks!
Thank you.
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