pogo44
Newbie
Hi everyone,
I'm working on my first ever circuit and PCB board for an automatic watering project that requires a long on/off time delay relay controller. I could really use some guidance from this knowledgeable community.
TL;DR: I'm working on a retro-style timer circuit using the CD4060 and NE555P. The CD4060 sets a frequency and divides it, with an output triggering and resetting the NE555. I need to ensure proper pull-down resistors and transistor interfaces to avoid false triggering and ensure reliable operation. Seeking advice on setup and improvements.
Project Overview:
Objective: To design an on/off timer circuit that can manage long on/off time delays.
Requirements:
On Time: Separately adjustable from the off time. Currently, I'm planning to set a frequency and use a binary ripple counter (CD4060) to divide it, effectively making the frequency much lower.
Off Time: Same approach as ON time.
Load: Capable of switching various voltages/currents. The relay will likely support 12V or the electric grid (230V in my case).
Accuracy: High accuracy isn't crucial, but I would like it to be repeatable. For instance, if I want an off delay of about 12 hours, I can set the approximate frequency required and select the correct output on the counter to divide it accordingly. A slight deviation of a few minutes is acceptable.
Interface: I plan to use an Excel sheet with pre-calculated capacitor/resistor values for certain frequencies. Would it be beneficial to use a potentiometer on the frequency circuit for fine adjustment?
Challenges I'm Facing:
Parts on Hand: I want to use the components I already have: NE555P, CD4060, 1/4W and 1/8W resistors, ceramic capacitors, transistors, etc. (I'll attach a photo of the labels on my component drawer. I have these parts because I enjoy fixing circuits with obviously broken/burned components.)
Avoiding Microcontrollers: I'd like to make this circuit without any microcontrollers, even though I know it would have been faster and easier.
Inexperience with Components: I have not used transistors or counters before, so I'm unsure if my current design would work. I haven't added any resistors to the transistors yet, but I know they are needed and plan to do so.
Resetting the Counter: I assume that directly connecting the output of my counter to itself to reset its count might cause issues and uncertainty. How would you go about fixing this? Should I use some sort of delay or an additional IC?
Any suggestions, schematics, or references to similar projects would be greatly appreciated. Thank you in advance for your help!
I CAN'T ADD PICTURES INTO THE POST, SO I WILL NAME THEM ACCORDINGLY IN THIS SHARE LINK
Link with pictures
Also, here is the KiCad project if it helps.
I tried to simulate it but was unsuccessful .
https://sf.solcloud.eu/d/9d19586b20d444fd948f/
Detailed Circuit Information:
Part 1: CD4060 Configuration
I'm using the CD4060 with the built-in oscillator to preset a frequency based on the amount of time I want the circuit to output the ON/OFF signal. The frequency is set with the RC part, and it requires a second resistor for reasons I haven't really looked into yet.
Once the frequency is set, it goes through the binary counter where I can divide it by choosing an output pin using the switch.
Part 2: Triggering the NE555
In this part, I'm trying to use the previously mentioned counter signal to pull the TR pin on the 555 low to trigger it. I'll ignore what this does to the ON part of the circuit until later on in the post.
Part 3: Tandem NE555 Timers
For the tandem part of the 555, once one of the 555s is triggered when the circuit is turned on while one of the physical buttons is held:
Summary and Key Points:
Best regards,
Nik
I'm working on my first ever circuit and PCB board for an automatic watering project that requires a long on/off time delay relay controller. I could really use some guidance from this knowledgeable community.
TL;DR: I'm working on a retro-style timer circuit using the CD4060 and NE555P. The CD4060 sets a frequency and divides it, with an output triggering and resetting the NE555. I need to ensure proper pull-down resistors and transistor interfaces to avoid false triggering and ensure reliable operation. Seeking advice on setup and improvements.
Project Overview:
Objective: To design an on/off timer circuit that can manage long on/off time delays.
Requirements:
On Time: Separately adjustable from the off time. Currently, I'm planning to set a frequency and use a binary ripple counter (CD4060) to divide it, effectively making the frequency much lower.
Off Time: Same approach as ON time.
Load: Capable of switching various voltages/currents. The relay will likely support 12V or the electric grid (230V in my case).
Accuracy: High accuracy isn't crucial, but I would like it to be repeatable. For instance, if I want an off delay of about 12 hours, I can set the approximate frequency required and select the correct output on the counter to divide it accordingly. A slight deviation of a few minutes is acceptable.
Interface: I plan to use an Excel sheet with pre-calculated capacitor/resistor values for certain frequencies. Would it be beneficial to use a potentiometer on the frequency circuit for fine adjustment?
Challenges I'm Facing:
Parts on Hand: I want to use the components I already have: NE555P, CD4060, 1/4W and 1/8W resistors, ceramic capacitors, transistors, etc. (I'll attach a photo of the labels on my component drawer. I have these parts because I enjoy fixing circuits with obviously broken/burned components.)
Avoiding Microcontrollers: I'd like to make this circuit without any microcontrollers, even though I know it would have been faster and easier.
Inexperience with Components: I have not used transistors or counters before, so I'm unsure if my current design would work. I haven't added any resistors to the transistors yet, but I know they are needed and plan to do so.
Resetting the Counter: I assume that directly connecting the output of my counter to itself to reset its count might cause issues and uncertainty. How would you go about fixing this? Should I use some sort of delay or an additional IC?
Any suggestions, schematics, or references to similar projects would be greatly appreciated. Thank you in advance for your help!
I CAN'T ADD PICTURES INTO THE POST, SO I WILL NAME THEM ACCORDINGLY IN THIS SHARE LINK
Link with pictures
Also, here is the KiCad project if it helps.
I tried to simulate it but was unsuccessful .
https://sf.solcloud.eu/d/9d19586b20d444fd948f/
Detailed Circuit Information:
Part 1: CD4060 Configuration
I'm using the CD4060 with the built-in oscillator to preset a frequency based on the amount of time I want the circuit to output the ON/OFF signal. The frequency is set with the RC part, and it requires a second resistor for reasons I haven't really looked into yet.
Once the frequency is set, it goes through the binary counter where I can divide it by choosing an output pin using the switch.
- Issue: I directly connected the Qn output to the CLR pin to reset the count. I think I still need to add a pull-down resistor to prevent false triggering of the reset pin. Is this correct?
- Uncertainty: I don't know whether the output Qn can even trigger its own CLR pin. In addition to triggering the clearing of the count, I want to use this momentary signal to trigger the NE555P in bistable mode to turn on its output with the help of a transistor.
- Doubt: How could a logic signal possibly trigger a transistor? Should I be using an op-amp?
Part 2: Triggering the NE555
In this part, I'm trying to use the previously mentioned counter signal to pull the TR pin on the 555 low to trigger it. I'll ignore what this does to the ON part of the circuit until later on in the post.
- AND Logic: Because I'm using the same signal that triggers the 555 to clear the counter, the AND circuit works as intended and only recognizes the 555 signal for now.
- Cycle: After another cycle, we should get another signal from the counter, which should trigger the other transistor in the AND logic, sending a reset signal to the 555 timer.
Part 3: Tandem NE555 Timers
For the tandem part of the 555, once one of the 555s is triggered when the circuit is turned on while one of the physical buttons is held:
- Output: The output turns on, sending power to the other 555 reset pin transistor and should be disabled for the duration of the first 555's cycle.
Summary and Key Points:
- Pull-Down Resistor: Add a pull-down resistor to the CLR pin of the CD4060 to prevent false resets.
- Transistor Interface: Use transistors to interface the CD4060 outputs with the NE555 timer’s TR and RST pins for reliable operation.
- Debouncing and Filtering: Use capacitors to filter any noise from the CD4060 outputs before they trigger the NE555 timers.
Best regards,
Nik
[MODERATOR ACTION]
Embeeded external hosted project files into this thread
Attachments
Last edited by a moderator: