sdk

+# STH1029-dat

+

+

+## board

+

+[Heart Rate Monitor, ECG, Single Lead, AD8232](https://www.electrodragon.com/product/single-lead-heart-rate-monitor-ad8232/)

+

+

+

+## tech

+

+- [[AC-blocking-dat]] - [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]] - [[LC-circuits-dat]] - [[NE555-Astable-dat]] - [[HLW8012-dat]] - [[STH1029-dat]] - [[current-transformer-dat]]

+

+## in

+

+- [[AD8232-dat]]

+

+[[sensor-bio-ECG-dat]] - [[sensor-bio-heart-rate-dat]] - [[sensor-bio-dat]]

+

+

+

+

+

+FEATURES

+- Small Form Factor (1inch X 1inch)

+- Specially Designed For Microcontrollers

+- Adjustable Gain – Improved Ruggedness

+- New On‐board 3.5mm Cable Port

+- Pins Fit Easily on Standard Breadboards

+

+APPLICATIONS

+- Video games

+- Robots

+- Medical Devices

+- Wearable/Mobile Electronics

+- Powered Exoskeleton suits

+

+What is electromyography?

+

+Measuring muscle activation via electric potential, referred to as electromyography (EMG), has

+traditionally been used for medical research and diagnosis of neuromuscular disorders. However,

+with the advent of ever shrinking yet more powerful microcontrollers and integrated circuits, EMG

+circuits and sensors have found their way into prosthetics, robotics and other control systems.

+

+

+

+

+

+1) Connect the power supply (two 9V batteries)

+- a. Connect the positive terminal of the first 9V battery to the +Vs pin on your sensor.

+- b. Connect the negative terminal of the first 9V battery to the positive terminal of the  second 9V battery. Then connect to the GND pin on your sensor.

+- c. Connect the negative terminal of the second 9V battery to the –Vs pin of your sensor.

+

+2) Connect the electrodes

+- a. After determining which muscle group you want to target (e.g. bicep, forearm, calf),  clean the skin thoroughly.

+- b. Place one electrode in the middle of the muscle body, connect this electrode to the  RED Cable’s snap connector.

+- c. Place a second electrode at one end of the muscle body, connect this electrode to  the Blue Cable’s snap connector. 

+- d. Place a third electrode on a bony or non‐muscular part of your body near the  targeted muscle, connect this electrode to the Black Cable’s snap connector.

+

+3) Connect to a Microcontroller (e.g. Arduino)

+- a. Connect the SIG pin of your sensor to an analog pin on the Arduino (e.g. A0)

+- b. Connect the GND pin of your sensor to a GND pin on the Arduino.

+

+

+

+- [[TL08-dat]] - [[amplifier-dat]]

+

+## Electrical Specifications

+

+| Parameter | Min | TYP | Max |

+| -------------------------------------------- | --------------- | --------------- | ---------------- |

+| Power Supply Voltage (Vs) | ±3V | ±5V | ±30V |

+| Gain Setting, Gain = 207*(X /1 kΩ) | 0.01 Ω (0.002x) | 50 kΩ (10,350x) | 100 kΩ (20,700x) |

+| Output Signal Voltage (Rectified & Smoothed) | 0V | - | +Vs |

+| Differential Input Voltage | 0 mV | 2-5 mV | +Vs/Gain |

+

+## EMG

+

+

+

+

+## AD8232 Sensor Module

+

+### Single-Lead Heart Rate Monitoring Front-End

+

+AD8232 is an integrated front-end designed for signal conditioning of cardiac bioelectric signals for heart rate monitoring.

+

+It is an integrated signal conditioning module for ECG and other bioelectric measurement applications. The device is designed to extract, amplify, and filter weak bioelectric signals in the presence of noise from motion or remote electrode placement. This design allows ultra-low power analog-to-digital converters (ADC) or embedded microcontrollers to easily acquire the output signal.

+

+AD8232 uses a two-pole high-pass filter to eliminate motion artifacts and electrode half-cell potentials. This filter is tightly coupled with the instrumentation amplifier structure to achieve single-stage high gain and high-pass filtering, thereby saving space and cost.

+

+AD8232 uses an unconstrained operational amplifier to create a three-pole low-pass filter, eliminating additional noise. Users can select the cutoff frequencies of all filters to meet the needs of different types of applications.

+

+To improve the common-mode rejection performance of system line frequency and other unwanted interference, AD8232 has a built-in amplifier for driven lead applications such as right leg drive (RLD).

+

+AD8232 includes a fast recovery feature that reduces the long settling tail of the high-pass filter. If the amplifier rail voltage experiences a signal glitch (such as lead-off), AD8232 will automatically adjust to a higher filter cutoff state. This feature allows AD8232 to achieve fast recovery, thus obtaining valid measurements as soon as possible after the leads are connected to the subject's electrodes.

+

+The guaranteed performance temperature range is 0°C to 70°C, and the operating temperature range is -40°C to +85°C.

+

+### Applications

+

+- Fitness and sports heart rate monitoring

+- Portable [[sensor-bio-ECG-dat]]

+- Remote health monitoring

+- Gaming peripherals

+- Bioelectric signal acquisition

+

+### Pin Descriptions

+

+| Number | Name | Description |

+| ------ | ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

+| 1 | HPDRIVE | High-pass driver output. HPDRIVE should be connected to the capacitor in the first high-pass filter. AD8232 drives this pin to keep HPSENSE at the same level as the reference voltage. |

+| 2 | +IN | Instrumentation amplifier positive input. +IN is typically connected to the left arm (LA) electrode. |

+| 3 | −IN | Instrumentation amplifier negative input. −IN is typically connected to the right arm (RA) electrode. |

+| 4 | RLDFB | Right leg drive feedback input. RLDFB is the feedback pin for the right leg drive circuit. |

+| 5 | RLD | Right leg drive output. The drive electrode (usually right leg) should be connected to the RLD pin. |

+| 6 | SW | Fast recovery switch pin. This pin should be connected to the output of the second high-pass filter. |

+| 7 | OPAMP+ | Operational amplifier non-inverting input. |

+| 8 | REFOUT | Reference voltage buffer output. The instrumentation amplifier output references this potential. REFOUT should be used as a virtual ground for any point in the circuit that requires a reference signal. |

+| 9 | OPAMP− | Operational amplifier inverting input. |

+| 10 | OUT | Operational amplifier output. This output provides the fully conditioned heart rate signal. OUT can be connected to the input of an ADC. |

+| 11 | LOD− | Lead-off comparator output. In DC lead-off detection mode, LOD− is high when disconnected from the −IN electrode, otherwise low. In AC lead-off detection mode, LOD− is always low. |

+| 12 | LOD+ | Lead-off comparator output. In DC lead-off detection mode, LOD+ is high when disconnected from the +IN electrode, otherwise low. In AC lead-off detection mode, LOD+ is high when either −IN or +IN electrode is disconnected, low when both are connected. |

+| 13 | SDN | Shutdown control input. Driving SDN low enters low-power shutdown mode. |

+| 14 | AC/DC | Lead-off mode control input. For DC lead-off mode, drive AC/DC low. For AC lead-off mode, drive AC/DC high. |

+| 15 | FR | Fast recovery control input. Driving FR high enables fast recovery mode; otherwise, drive it low. |

+| 16 | GND | Power ground. |

+| 17 | +VS | Power supply pin. |

+| 18 | REFIN | Reference voltage buffer input. REFIN (high impedance input) can be used to set the level of the reference voltage buffer. |

+| 19 | IAOUT | Instrumentation amplifier output pin. |

+| 20 | HPSENSE | Instrumentation amplifier high-pass sense input. HPSENSE should be connected to the R and C node that sets the high-pass filter corner frequency. |

+| EP | Exposed Pad | Exposed pad. The exposed pad should be connected to GND or left unconnected. |

+

+

+## demo code

+

+- [[bitalino-android-example-master.zip]] - [[MuscleSensor_Arduino.zip]] - [[MuscleSensor_Processing.zip]]

+

+

+## ref

+

+

+# ESP32-S3-HDK-dat

+

+- [[ESP32-S3-WROOM-1-dat]] - [[ESP32-S3-module-dat]] - [[ESP32-S3-chip-dat]]

+

+- [[ESP32-S3-board-dat]]

+

+- [[ESP32-HDK-dat]] - [[ESP32-S3-HDK-dat]] - [[ESP32-C3-HDK-dat]]

+

+## strap pins

+

+

+

+

+## build

+

+- [[SPI-dat]] - [[serial-dat]] - [[ESP32-S3-HDK-dat]] - [[74HC4067-dat]] - [[LED-RGB-dat]]

+

+

+

+

+

+### program

+

+

+

+

+## ref

+

+- [[ESP32-S3-dat]]

+

+# HLW8012-dat

+

+- [legacy wiki page ](https://w.electrodragon.com/w/HLW8012)

+

+## Chip Info

+

+

+

+### Hardware Design Note

+* Board AC Mains is be NOT isolated.

+* Better use optical-coupler to send isolated signal to your MCU.

+* MCU better use seperated power supply to HLW8012.

+

+#### other note

+* Built-in crystal, 2.43V voltage reference source and power monitoring circuit

+* 5V single power supply, operating current less than 3mA

+

+## Application

+

+

+

+As shown in Figure 3, the power supply the HLW8012 should be in parallel with two small capacitors to filter out the noise from the grid.

+

+- The signal of current channel is provided by the current diverter.

+- The signal of voltage channel is provided by the resistor network.

+

+CF, CF1, SEL connect to the input port of the MCU. MCU measure the pulse periods of CF and CF1, then calculate the active power, current RMS and voltageRMS

+

+

+#### Sample resistor

+

+* Sample Resistor is 0.002R, 2mR (diameter 2.5mm, rate current is 20A. space is 10mm, height 7.5mm, "door" shape).

+

+

+## Calculatoin

+

+

+

+

+

+ F_cf = (V1xV2x48)/(V_ref)^2 x (F_osc/128)

+ F_cf1 = (V1x24)/(V_ref) x (F_osc/512)

+ F_cfu = (V2x2)/V_ref x (F_osc/512)

+

+Note

+

+* Fcf = Power, Fcf1 = current, Fcfu = voltage

+* V1: Voltage signal on the current channel pin

+* V2: Voltage signal on voltage channel pin

+* Fosc: built-in crystal, the typical frequency of about 3.579MHz;

+* Vref: built-in reference source, the typical voltage is 2.43V

+

+## Use with ESP8266

+

+* The demo code will monitoring the power, current, voltage and frequency, you can monitor it via telnet to see remote debug output, same as serial output, but safe when AC main power connected.

+* Pin definition to esp8266 please see the comments in sketch

+* Also can calibrate the parameters, see the comments in sketch

+* Enter SSID and password in the sketch, run the demo code first to see IP address

+* Connect to AC main power, login remotely via telnet, in windows for example, command: telnet 192.168.0.100

+

+* [Demo code here](https://github.com/Edragon/esp8266_arduino/tree/master/HLW8012/remote_debug)

+

+

+## Establishing a Clean Ground for HLW8012 Power Meter IC

+

+To ensure accurate performance of the HLW8012 power meter IC in current shunt measurement, voltage measurement, analog (oversampling ADC) operations, and digital output interfaces, it is recommended to implement the following grounding strategy on the PCB:

+

+1. **Create a Ground Region**: Design a ground area beneath the IC that loops around the four analog pins on the left side. This ground encirclement should be formed using a 0.5-centimeter-wide copper trace.

+

+2. **Connect Key Components to the Ground Encirclement**:

+ - The IC's ground pin.

+ - The ground ends of the 0.033 µF capacitors associated with the current shunt. Ensure these PCB traces are symmetrical, balanced, and as short as possible.

+ - The two capacitors used for the +5V VDD bypass filter.

+

+Additionally, some reference designs suggest inserting a 10-ohm resistor in the path from the +5V voltage regulator to these two capacitors and the IC's VDD pin. This configuration creates a low-pass filter that reduces EMI/RFI interference entering the IC, thereby preventing miscounts or unintended power-on resets. In professional designs requiring high robustness, circuits must withstand significant electric and magnetic fields from high-power transmitters and antennas without errors. Place the 10-ohm resistor close to the two capacitors to minimize potential antenna effects.

+

+By implementing this grounding approach, the HLW8012 IC can achieve precise and reliable power measurement.

+

+- [[AC-blocking-dat]] - [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]] - [[LC-circuits-dat]] - [[NE555-Astable-dat]] - [[HLW8012-dat]]

+

+## Demo

+

+https://www.youtube.com/watch?v=0aiuwRB8Uic

+

+

+## DS

+

+- [[HLW8012-HLW-REV1.3.pdf]]

+

+## demo code

+

+- https://github.com/Edragon/arduino-main2/tree/main/tech/Sensor/1-Current/HLW8012

+- https://github.com/Edragon/arduino-esp8266/tree/master/Sketchbook/APP/HLW

+

+

+## ref

+

+- [[HLW8012-dat]] - [[HLW8032-dat]] - [[HLW-dat]] - [[ac-mains-dat]] - [[power-meter-dat]] - [[power-sensor-dat]]

+

+Boards - [[OPM1126-dat]]

+

+- [[OPM1126]] - [[HLW8012]]

+

+

+

+# 74HC4067-dat

+

+## SCH

+

+

+

+- [[ESP32-S3-HDK-dat]] - [[74HC4067-dat]]

+

+

+## ref

+

+

+- [[analog-device-dat]] - [[ADE7953-dat]]

+

+

+

+

+# ADE7953-dat

+

+- [[analog-device-dat]] - [[ADE7953-dat]]

+

+- [[meter-energy-dat]] - [[sensor-energy-dat]] - [[meter-dat]]

+

+- [[current-transformer-dat]] - [[ADE7953-dat]]

+

+- [[ACDC-dat]] - [[meter-energy-dat]]

+

+Single Phase, Multifunction Metering IC with Neutral Current Measurement

+

+

+

+## APP SCH

+

+

+

+SCH2

+

+- [[ESP32-S3-HDK-dat]] - [[74HC4067-dat]] - [[ADE7953-dat]]

+

+

+

+channels INA and INB

+

+

+

+

+## layout

+

+

+

+LAYOUT GUIDELINES

+

+Figure 78 presents a basic schematic of the ADE7953 together with its surrounding circuitry, decoupling capacitors at pins VDD, VINTA, VINTD, and REF, and the 3.58 MHz crystal and its load capacitors. The rest of the pins are dependent on the particular application and are not shown here.

+

+Figure 77 presents a proposed layout of a printed circuit board (PCB) with two layers that have the components placed only on the top of the board. Following these layout guidelines will help in creating a low noise design with higher immunity to EMC influences.

+

+The VDD, VINTA, VINTD, and REF pins each have two decoupling capacitors, one of μF order and a ceramic one of 220 nF or 100 nF. These ceramic capacitors need to be placed closest to the ADE7953 as they decouple high frequency noises, while the μF ones need to be place in close proximity.

+

+The exposed pad of the ADE7953 is soldered to an equivalent pad on the PCB. The AGND, DGND, and PULL_LOW pins traces of the ADE7953 are then routed directly in to the PCB pad.

+

+The bottom layer is composed mainly of a ground plane surrounding as much as possible the through hole crystal pins.

+

+

+## extend

+

+- [[multiplexer-dat]]

+

+

+

+

+## ref

+

+

+- [[analog-device-dat]] - [[ADE7953-dat]]

+

+

+

+# NE555-Astable-dat

+

+- [[AC-blocking-dat]] - [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]] - [[LC-circuits-dat]] - [[NE555-Astable-dat]]

+

+

+

+## ⚙️ Mode 1: Astable (Oscillator)

+

+### 🔁 Generates a continuous square wave

+

+### 🔧 Wiring:

+

+```

+ VCC

+ |

+ [R1]

+ |

+ +------ Pin 7 (DIS)

+ | |

+ [R2] [C1]

+ | |

+ Pin 6 -----+ |

+ Pin 2 -----|--+

+ |

+ GND

+

+- Pin 4 (RESET) → VCC

+- Pin 5 (CTRL) → 0.01µF to GND

+- Pin 3 = Output

+```

+

+### 🧮 Frequency & Duty Cycle:

+

+```

+T = 0.693 × (R1 + 2×R2) × C1

+f = 1 / T

+Duty Cycle ≈ (R1 + R2) / (R1 + 2×R2)

+```

+

+---

+

+## example 1.

+

+This is a **PWM generator circuit** using a 555 Timer IC configured in **astable mode**, used to control a DC motor via a MOSFET. The duty cycle is adjustable using a potentiometer.

+

+---

+

+## 📦 Circuit Summary

+

+| Pin | Name | Description |

+| --- | --------------- | ----------------------------------------------------------- |

+| 1 | GND | Connected to ground |

+| 2 | Trigger | Connected to timing capacitor C2 via noise filters (C3, C2) |

+| 3 | Output | PWM signal output to MOSFET gate |

+| 4 | Reset | Tied to VCC to avoid accidental reset |

+| 5 | Control Voltage | Decoupled with 0.01 µF (C4) for noise immunity |

+| 6 | Threshold | Connected to timing network |

+| 7 | Discharge | Discharges timing capacitor via R1 |

+| 8 | VCC | Power supply (with decoupling capacitor C1 = 220 µF) |

+

+---

+

+## 🧩 Key Components

+

+| Component | Value | Function |

+| --------- | ---------- | ------------------------------------- |

+| R1 | 1 kΩ | Sets discharge time |

+| R2 | 100 kΩ pot | Sets charge time (duty cycle control) |

+| D1 | 1N4148 | Separates charge and discharge paths |

+| C1 | 220 µF | Power decoupling |

+| C2, C3 | 1 nF | Trigger debounce / noise filtering |

+| C4 | 0.01 µF | Filters pin 5 (control voltage) |

+| MOS | N-channel | PWM-driven motor control |

+

+---

+

+## 🔄 Operation

+

+1. **C2 charges** through **R2** and **D1**.

+2. When voltage on C2 reaches 2/3 VCC → 555 output turns **LOW**.

+3. **C2 discharges** through **R1** and pin 7.

+4. When voltage drops below 1/3 VCC → 555 output goes **HIGH**.

+5. This loop creates a **PWM signal** at pin 3.

+6. PWM signal drives the **MOSFET**, which controls motor speed.

+

+---

+

+## ⚙️ Features

+

+- Adjustable **duty cycle** via R2 (100k potentiometer)

+- Stable operation with **decoupling capacitors**

+- Simple and low-cost motor control solution

+- Output PWM can be used to drive **DC motors**, **LEDs**, or other loads via a **MOSFET**

+

+---

+

+## ✅ Notes

+

+- Make sure the MOSFET is appropriate for your motor's voltage and current.

+- You can add a **flyback diode** across the motor for protection.

+

+

+

+

+

+

+

+

+## example 2. ⚙️ NE555 as PWM Generator with Potentiometer

+

+### 📌 Purpose

+

+Generate a variable PWM (Pulse Width Modulated) signal using an NE555 timer. Adjust the duty cycle with a potentiometer to control devices like:

+- Motor speed

+- LED brightness

+- Servo-like applications (via low-pass filtering)

+

+---

+

+### 📦 Parts Required

+

+| Part | Value |

+| -------------- | -------------------------------------------------------- |

+| NE555 Timer IC | 1× |

+| Potentiometer | 10kΩ or 100kΩ |

+| Diodes | 2× 1N4148 (or any fast switching diodes) |

+| Capacitor | 1× 1µF to 10µF (electrolytic or ceramic) |

+| Power Supply | 5V or 12V DC |

+| Load | Optional (e.g. LED + resistor, transistor + motor, etc.) |

+

+---

+

+### 🔌 Schematic (Text Diagram)

+

+```

+ VCC (+)

+ |

+ +------+

+ | |

+ [R] [D1]

+ | |

+ +------+

+ | |

+ [POT] [D2]

+ | |

+ +------+

+ |

+ Pin 7 (DIS)

+ |

+ [C1] to GND

+ |

+Pin 6 --------+

+Pin 2 --------+

+Pin 4 → VCC

+Pin 5 → 0.01µF to GND

+Pin 1 → GND

+Pin 3 → PWM Output

+```

+

+#### Pin Functions

+- **Pin 3**: PWM output

+- **POT**: Varies charge/discharge ratio, changing duty cycle

+- **Diodes (D1/D2)**: Separate charge/discharge paths

+

+---

+

+### ⚙️ How It Works

+

+- The NE555 is in **astable mode**.

+- The **two diodes** split the charge/discharge paths.

+- The **potentiometer** controls the ratio of charge to discharge time.

+- This changes the **duty cycle** while keeping frequency fairly stable.

+

+---

+

+### 📐 Formulas (Approximate)

+

+#### Charge time (output HIGH):

+```

+T_high = 0.693 × (R1 + variable portion of POT) × C1

+```

+

+#### Discharge time (output LOW):

+```

+T_low = 0.693 × (fixed portion of POT) × C1

+```

+

+#### Frequency:

+```

+f = 1 / (T_high + T_low)

+```

+

+#### Duty Cycle:

+```

+Duty = T_high / (T_high + T_low)

+```

+

+By adjusting the potentiometer, you change the ratio between T_high and T_low → **controlling duty cycle**.

+

+---

+

+### ✅ Tips

+

+- Use **small capacitor** (like 1µF) for higher frequency PWM (kHz range).

+- Add a **buffering transistor** on output if driving a motor or power load.

+- For smoother motor/LED control, consider adding a **low-pass filter** (R + C) on output to convert PWM to analog-like voltage.

+

+---

+

+### 🧪 Use Case: DC Motor Speed Control

+

+1. NE555 PWM output → base of NPN transistor (e.g., 2N2222 or TIP120)

+2. Motor connected to collector and power supply

+3. Adjust POT → duty cycle changes → motor speed changes

+

+

+

+

+## ref

+

+

+# AC-blocking-dat

+

+

+- [[AC-blocking-dat]] - [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]]

+

+

+## Types of AC Blocking Components

+

+**AC blocking components** are used to **prevent AC signals from passing** while **allowing DC** to flow. These are useful in filtering, power supply, and signal control applications.

+

+---

+

+### 1. **Inductors (Coils) 🧲**

+

+- **Function:** Oppose changes in current, especially high-frequency AC.

+- **Blocks:** AC signals (especially high frequency), passes DC.

+- **Usage:**

+ - Power supply filtering

+ - Chokes in DC lines

+ - EMI suppression

+

+---

+

+### 2. **Ferrite Beads**

+

+- **Function:** Similar to inductors; resist high-frequency AC noise.

+- **Blocks:** High-frequency AC interference

+- **Passes:** DC and low-frequency signals

+- **Usage:** Noise filtering in power lines and signal lines

+

+---

+

+### 3. **Low-Pass Filters (RC or LC)**

+

+- **Function:** Combine resistors and capacitors/inductors to block AC above a certain frequency.

+- **Blocks:** High-frequency AC

+- **Passes:** DC or low-frequency signals

+- **Usage:** Signal conditioning, analog circuits

+

+---

+

+### 4. **Zener Diodes or TVS Diodes (for AC spikes)**

+

+- **Not direct AC blockers**, but suppress voltage spikes (AC noise).

+- **Usage:** Surge protection on DC lines.

+

+---

+

+## Summary Table

+

+| Component | Blocks AC | Passes DC | Common Use Case |

+|------------------|-----------|-----------|--------------------------------|

+| Inductor | ✅ | ✅ | DC line filtering, power supply |

+| Ferrite Bead | ✅ | ✅ | High-frequency noise suppression |

+| Low-Pass Filter | ✅ (partial) | ✅ | Signal smoothing, power rails |

+| Zener/TVS Diode | ✅ (spikes) | ✅ | Surge protection |

+

+> 🧲 **Inductors** are the most direct and widely used components for **AC blocking** while passing DC.

+

+## ref

+

+

+# LC-circuits-dat.md

+

+

+- [[AC-blocking-dat]] - [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]] - [[LC-circuits-dat]]

+

+

+## What is an LC Circuit?

+

+An **LC circuit** is a resonant circuit made of:

+

+- **L (Inductor):** Stores energy in a magnetic field.

+- **C (Capacitor):** Stores energy in an electric field.

+

+---

+

+### 🔁 How It Works

+The LC circuit continuously transfers energy back and forth:

+1. The capacitor discharges through the inductor.

+2. The inductor builds a magnetic field.

+3. The magnetic field collapses, recharging the capacitor with opposite polarity.

+4. The cycle repeats — this creates **oscillations**.

+

+---

+

+### 📶 Resonance

+An LC circuit has a **natural resonant frequency**:

+

+\[

+f = \frac{1}{2\pi\sqrt{LC}}

+\]

+

+Where:

+- `f` = frequency (in Hz)

+- `L` = inductance (in henries)

+- `C` = capacitance (in farads)

+

+---

+

+### 🧰 Common Uses

+- Radio tuners (to select a station)

+- Filters (high-pass, low-pass, band-pass)

+- Oscillators (to generate signals)

+- Impedance matching networks

+

+---

+

+### 📷 Example

+An AM radio uses an LC circuit to **tune to a specific frequency**, like 1000 kHz, by adjusting `L` or `C`.

+- [[74HC4067-dat]]

+# current-transformer-dat

+

+- [[sensor-current-dat]]

+

+- [[current-transformer-dat]] - [[ADE7953-dat]]

+

+- [[filter-low-pass-dat]] - [[filter-dat]]

+

+== a low-pass filter (1 kΩ / 33 nF)

+

+## tech

+

+

+- [[ZMCT103-dat]] == 1000:1 [[current-dat]] - [[current-transformer-dat]]

+

+- [[ZMPT107-dat]] == 1000:1000 [[voltage-dat]] - [[ac-voltage-transformer-dat]]

+

+

+

+## boards

+

+- [[SVC1038-dat]] - [[SVC1042-dat]]

+

+

+## PCB Mount

+

+- [[zeming-dat]] - [[EDCT-dat]]

+

+- [[ZMCT103-dat]] == 1000:1 [[current-dat]] // - [[ZMPT107-dat]] == 1000:1000 [[voltage-dat]] || - [[current-transformer-dat]]

+

+## Open Split Core Current Transformer

+

+- [[YHDC-dat]]

+

+

+## BX-CT Specifications

+

+

+

+| left | middle | right |

+| ------ | ------ | ----- |

+| 5A | 15A | 30A |

+| 2000:1 | 2000:1 | 1500: |

+

+

+## DL-CT08CL10-2000/1 = Specifications

+

+"Miniature current transformer, small AC through-core type, class 0.1 precision, high-frequency transformer, lead type, 1000:1"

+

+Here's a breakdown:

+

+微型电流互感器: miniature current transformer

+

+小型交流穿心式: small AC through-core type

+

+0.1级精密: class 0.1 precision

+

+高频互感器: high-frequency transformer

+

+引线式: lead type (with wire leads)

+

+1000:1: transformation ratio

+

+## Other Form

+

+

+

+

+

+## ZHT103U

+

+ZHT103U series, current output type, with wire leads

+

+**Specifications:**

+- Accuracy class: 0.5

+- Case material: Engineering plastic, flame retardant

+- Dielectric strength: MQ / V/min

+- Features: Fully potted, strong environmental resistance, high accuracy, good consistency, flexible installation, wide linear range

+- Frequency range: KHz

+- Input type: Single pass-through input, secondary wire output

+- Insulation resistance: ≤35'32001000MQ / 500V/min

+- Linear range: 0~10A

+- Load resistance: 100Ω

+- Operating temperature: -35℃~+75℃

+- Output current (rated): 5mA

+- Output type: Lead wire

+- Rated input current: 5A

+- Storage temperature: -40℃~+80℃

+- Transformation ratio: 1000:1

+- Typical applications: Power network meters, power transmitters, ammeters, measurement and control devices, etc.

+

+

+

+

+## SCH

+

+16 channels

+

+

+

+## ref

+

+

+- [[current-sensor-dat]]

+

+- [[current-transformer]]

+

+- [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]]

+

+

+- [[EMI-dat]]

+

+

+

+# filter-low-pass-data

+

+- [[AC-blocking-dat]] - [[filter-dat]] - [[filter-high-pass-dat]] - [[filter-low-pass-dat]] - [[low-pass-rc-filter-dat]] - [[LC-circuits-dat]]

+

+- [[NE555-Astable-dat]] - [[HLW8012-dat]] - [[STH1029-dat]] - [[current-transformer-dat]]

+

+

+## ref

+

+

+

+

+- [[meter-dat]] - [[meter-resistance-dat]] - [[multimeter-dat]] - [[meter-current-dat]] - [[meter-voltage-dat]] - [[meter-voltage-current-dat]] - [[meter-energy-dat]]

+

+

+# meter-energy-dat

+

+- [[meter-energy-dat]] - [[sensor-energy-dat]] - [[meter-dat]]

+

+## tech

+

+- [[analog-device-dat]] - [[ADE7953-dat]]

+