I am trying to make an automatic feeder. I have a timer which is an off the shelf item that operates on 6vdc that's going to be tripping solenoids that will allow the feed to be distributed. the issue is the shortest period of time i can set the timer to come on is 1 sec which can be forever when it comes to electrical stuff. the timer only has 1 output so I have all the solenoids in series with a NO/NC switch between them. Checkout the attached image. I want to use a 555 timer circuit to allow the solenoids to get power for a fraction of a second but i cant figure out what type or the exact components. there's astable, bistable, monostable........ I wasn't planning on having constant power to the timer circuit I was hoping to have the first 3/4 of a second of power to charge the timer circuit then the last 1/4 of a second to be allowed to pass on to the solenoids. so I guess i need advice on the type of timer and with the layout & exact components.

 

You need to get more specific about the voltage and current. (I have to go to work now.)

 

Solenoids are in parallel, current requirement unknown. Use 2 555's as one-shots, or one 556.

 

It sounds a lot like you want to use a monostable 555-timer. For these, you can specify how long the output is "on." You trigger it manually, with a push-button, for example. The 555 can easily do 1 second on. If the 555 is not able to deliver enough current to actuate your relays, consider having it drive a transistor to power the relays.

I don't understand what you mean when you say that you want to "charge" the timing circuit. Are you trying to power this dynamically? You're going to need a power supply of some kind regardless.

 

Using a standard 6 volt battery. I guess I am confused what series & parallel means when it comes to electronic components. I am thinking I need a monosable 555 as well but not 100% sure. Let me see if I can give a brief description of how i want this thing to work.
the timer is going to be set to supply power out to the solenoids(sol) 4 times a day for 1 second. so Feeding time 1:timer goes off power is sent to switch(sw)1, sw1 is closed so power is sent to sol1, it actuates opening door1 thus opening sw1. Feeding time 2: timer goes off power is sent to sw1, sw1 is open so power is sent to sw2, sw2 is closed power is sent sol2, it actuates opening door2 thus opening sw2. feeding time 3:timer goes off power is sent to sw1, sw1 is open so power is sent to sw2, sw2 is open so power is sent to sw3, sw3 is closed power is sent sol3, it actuates opening door3 thus opening sw3. and so on and so on. the issue is with the timer on for ONE whole second all the doors can be opened at one time thats why i need a delay. the switch I am using is a maganetic SPDT switch so the closer I place the 2 halves toghter the longer they switch stays closed as the door falls away but its not enough of a delay.

 

i need help making a monostable 555 circuit that will power on a relay for a 1/8 to a 1/4 of a second allowing a 0.5amp current from a 6 volt battery to operate the solenoids.

 

What controles the switches? For a start, here is the one-shot. It is triggered as timer powersup ckt & times out according to setting of R3 & C2, o to .5 sec. Increase C2 if longer time is desired. D1, any in 1N 4XXX series. I would prefer a MOSFET, logic level, for U2, but do not have a number.

 

Note that using operating time of a solenoid to control the sequence of events is not a completely reliable way to control the doors. As the temperature changes or the components age, the original timing that worked may start to give faulty operation. Better would be to use a counter, such as a CD4017, to sequence from one door to the next. This would require separate wires to each solenoid. Would that be a problem?

The timer circuit must have continuous power, or it won't work, but you can use timers that take a very small current. What is the "timer" that you were referring too.

Are you are up to building a circuit using some 555's and a few other ICs?

 

Bernard, I wasnt planning on putting a switch before the timer but the over all diagram you provided is a good starting point for me thanks a bunch.
Crutschow, the timer is used for feeding game animals like deer & elk etc. but they typically operate a motor that spins so the shortest time period i can set it for is a second. I like the idea of a PCB that can do what you are suggesting, would it get expensive, how would the counter get reset? One PCB & a sensor to reset the counter would be better then all the spdt switches i have planned.

 

........................
Crutschow, the timer is used for feeding game animals like deer & elk etc. but they typically operate a motor that spins so the shortest time period i can set it for is a second. I like the idea of a PCB that can do what you are suggesting, would it get expensive, how would the counter get reset? One PCB & a sensor to reset the counter would be better then all the spdt switches i have planned.

You could hard-wire the circuit on a breadboard type circuit board which would not be particularly expensive. The boards, such as one of these, only cost a few dollars. The circuit would likely contain a couple 555 timers, 3 simple integrated circuits, a power MOSFET and diode to drive each solenoid, plus some miscellaneous capacitors and resistors. I wouldn't think the total cost would be more than $20-$30 U.S.

The counter would just continually cycle through all the solenoids sequentially without stopping, so no counter reset would be needed. Or do you need the feeders to be off for a long period, like overnight?

 

Does your timer give a one sec. closed contact every 6 hours?? Depending on timing requirements a 4060 IC will give a low power timing function, just need to know your timing requirements.

 

Crutschow, I need a reset because I might go restock the feeder at different times of the day. I have an "on call" schedule so I want to feed 4 times a day & be set up to feed for 3 days that's 12 doors/solenoids. some days I will be there every day but others I might be gone for 2/3 days, so when i'm there every day I wont need it to cycle through all the solenoids. just the 1st 4 or 5. so a sensor that will reset the counter when I open the door to the feeder is what i think will work best. can a 4060 ic be reset?

 

Bernard, yes the timer will give a closed contact for 1 second at the times i set it for which will be 4 times a day, about 5 hours between feedings. what did you mean by "a 4060 IC will give a low power timing function" ?

 

The 4096 is a 14 stage counter with optioanl oscillator with added 2 Rs & a C; reset & inhibit included. Frequency can be set so that 14th stage resets @ every 5 hours, or as desired. A 4017, divide by 10, then gives 9 useable time slots & can be cascaded for any number desired. Each output would connect to a 2 in AND gate which allows a single .2 sec one shot to control all stages, & a solinoid driver for ea. stage.

 

Ok I couldnt solve my timing issue mechanically so I have to figure this out with a circuit. I need to replace the relay with a cuircuit that will put out a pulse signal instead of the 1 second current the timer puts out. have a look at the image & tell me what you think. I have been playing with a 555 timer but can't get it figured out, been trying different resistors but can't seem to find the right combo. do need to be playing with the capacitors as well or what?

 

How many feeders do you plan to have, just 4 or 4 for every day up to 3 days?
Are feeding times spaced equally thru out the day, or closer during daylight?

 

How many feeders do you plan to have, just 4 or 4 for every day up to 3 days?
Are feeding times spaced equally thru out the day, or closer during daylight?

12 Feedings total, 4 a day for 3 days. the timer can be set to go off 6 times a day so every day is the same.but i only want to feed at 6am, 11am, 4pm, & 9 pm. the reason I have the latches is series with the magnetic spdt switch is so power goes to the one needed which is always the bottom one, kinda drew it wrong but anyway. so the latch holds the tray when the timer goes off the relay opens which allows the signal to go to the latch which cause it to actuate letting the tray fall down pulling the magnet away from the switch allowing it to open and the signal to pass the the next latch. right now i have a full scale mock up of the whole thing & what is happening is the switch opens too fast and allows the next latch to receive a signal & actuate dropping the next tray. I the timers shortest operating time is a second so I have to figure out a way to shorten that up. i've been messing with a 555 circuit but dont have that figured out yet.

 

Doing away with magnetic SWs, as each of 4 latches is sequentially triggered every 5 hrs. starting at 6 AM, then repeats with another set of 4 the next day, & next. Latch energized time does not seem to me as critical, one sec ok , just uses a bit more power? " they tell me that a μC is the way to go, but that would be up to others, I'll think on a hard wire version.

 

what is a μC?

 

what is a μC?

A μC is a microcontroller, i.e., a computer on a chip. This would be a good application for one, and would greatly reduce the component count. However, it requires programming, which may be more learning than you want to tackle at this time.