From a25c8e29e67e81197e9a9dd342b3d23656274731 Mon Sep 17 00:00:00 2001 From: Mr-Fantastic6626 Date: Sun, 23 Aug 2026 18:36:40 +0530 Subject: [PATCH] Create README.md --- README.md | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 README.md diff --git a/README.md b/README.md new file mode 100644 index 0000000..0ed5d6c --- /dev/null +++ b/README.md @@ -0,0 +1,22 @@ +PROJECT PROPOSAL: Precision Analog Thermal Regulator Circuit + +PCB Design Idea & Basic Functionality: + +1. PCB Design Idea: +The core idea is an open-source, standalone Analog Thermal Regulator PCB designed for closed-loop liquid temperature control (such as pasteurization, fermentation, or laboratory heating baths). + +Instead of relying on expensive microcontrollers, digital displays, or code that can freeze, this design uses a purely analog feedback loop built around an LM324 operational amplifier. It is designed as a compact, double-sided (2-layer) through-hole board so that it can be easily manufactured, hand-soldered, and deployed in low-cost or rural settings. + +2. Basic Functionality: + +Live Temperature Sensing: An external probe (NTC thermistor or RTD) connects to the board, converting liquid temperature into a proportional voltage signal fed to the LM324's inverting input (-). + +Adjustable Setpoint Control: An onboard potentiometer forms a simple voltage divider connected to the LM324's non-inverting input (+). Turning the knob changes the reference voltage (V ref), allowing the user to set any desired temperature threshold (e.g., 72∘ C for milk pasteurization or 45 ∘C for yogurt making). + +Comparator Action with Hysteresis: The LM324 constantly compares the sensor voltage against the setpoint voltage. A built-in resistor hysteresis loop creates a narrow deadband buffer, preventing the relay from rapidly turning on and off ("chattering") when the temperature fluctuates right at the target boundary. + +Transistor Power Switching: When the liquid drops below the setpoint, the op-amp output goes HIGH, triggering a BC547 NPN transistor switch to drive a high-power heating relay. + +Inductive Spike Protection: A 1N4007 flyback diode placed across the relay coil suppresses voltage spikes when switching off, protecting the on-board components. + +Visual Status: An onboard LED illuminates whenever the heating element is actively powered.