In this post we'll study two simple externally triggered timer circuits for two different application needs, the ideas were requested by Mr. Alan and Ms.Stevanie
I only wish I understood electronics as you do.
Would you please help me with a simple timer circuit which would be adjustable for up to 30 seconds and be capable of powering a small pull in solenoid .
The circuit would be triggered by a magnetic reed switch in in two positions and must operate when either of the switches is triggered.
It must also reset automatically each time the reed switch opens. using a 9 volt battery would be optimal.
Any help you might provide would be extremely appreciated as this circuit would be used to control a small door providing the in /out access of animals at our non profit animal shelter in Florida.
Abandoned Pet Rescue
Fort Lauderdale, Florida
Referring to the diagram above the proposed solenoid timer with reed switching can be seen configured across a single timer/counter chip 4060.
As long as the reed switches are not triggered, the pin12 of the IC stays high through the 1M resistor, however if either one of the reed switches is triggered, the BJT is forced to conduct and ground pin12 of the IC which in turn gets reset and triggers the solenoid via the TIP127 transistor, the IC now begins counting. After 30 seconds (which may be varied or customized as per individual preference via the 1M pot), pin3 of the IC goes high causing the TIP127 to deactivate itself and the solenoid.
The positive feedback through diode 1N4148 to pin11 makes sure that the IC gets latched in this position until the reed switch is released and the IC gets reset to its original state.
I am Student of Dwi Raya University from Indonesia,
i have request for you to make Timer with 2 Selector Timing Schematics.
If this Timer is :
- select Button 1 ON, Timer work 3 Hours ON and 3 Hours OFF will be continuously Repeat as long as power supply is available
- select button 2 ON, Timer work 6 Hours ON and 6 Hours OFF will will be continuously Repeat as long as power supply is available
Please Help me Sir,
Thanks and Best Regards,
As per the request, the 3/6 hour selectable timer circuit may be studied above. Again a 4060 comes to the rescue and implements the application by including minimum number of parts.
The IC is configured in its standard timer configuration.
The 3.3M pot along with the 0.47uF capacitors determine the preferred adjustable time interval across the shown pinout 3 and 2.
The pin3 is set to provide the required delay of 6 hours, so that pin2 allows to acquire a 50% less that is a 3 hour delay option.
The above is appropriately selected through a SPDT switch wired as shown in the diagram.
The feedback diode ensures a latching action which may be simply removed if a continuous ON/OFf sequence is desired by the user, indefinitely.
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