The SMIH-05VDC-SL-A is a 5V single-channel electromagnetic relay used for switching high-voltage or high-current loads using low-voltage control signals.
It allows a microcontroller (5V logic) to safely turn on/off appliances, lights, fans, motors, or pumps that operate at AC (110–250V) or DC (up to 30V).
The “SL-A” type is known for high reliability, compact PCB size, and 10A current handling capability.
Specifications:
| Feature | Description |
|---|---|
| Type | Electromagnetic relay |
| Coil Voltage | 5 V DC |
| Coil Resistance | ~70 Ω |
| Contact Type | SPDT (Single Pole Double Throw — 1 Form C) |
| Contact Rating | 10 A @ 250 VAC or 10 A @ 30 VDC |
| Number of Pins | 6 pins (2 coil + 3 contact + 1 support) |
| Mounting Type | PCB mounting |
| Contact Material | Silver Alloy |
| Operate Time | ≤ 10 ms |
| Release Time | ≤ 5 ms |
| Dielectric Strength | 1500 VAC between coil and contacts |
| Insulation Resistance | ≥ 100 MΩ (at 500 VDC) |
| Mechanical Life | 10 million operations |
| Electrical Life | 100,000 operations at rated load |
| Operating Temperature Range | -40°C to +85°C |
Pin Configuration (6 Pins)
| Pin | Function | Description |
|---|---|---|
| 1 | Coil (+) | Connect to +5V DC |
| 2 | Coil (–) | Connect to GND (through transistor if using MCU) |
| 3 | Common (COM) | Common terminal of the switch |
| 4 | Normally Open (NO) | Connected to COM when coil is energized |
| 5 | Normally Closed (NC) | Connected to COM when coil is not energized |
| 6 | Support Pin | Mechanical or NC/NO duplicate depending on version |
How it works:
-
When no signal, COM → NC is connected.
-
When 5V coil is energized, COM → NO is connected.
Electrical Characteristics
| Parameter | Typical Value |
|---|---|
| Nominal Coil Voltage | 5 V DC |
| Coil Resistance | 70 ±10% Ω |
| Nominal Coil Power | ~0.36 W |
| Operate Voltage (max) | ≤ 3.75 VDC |
| Release Voltage (min) | ≥ 0.5 VDC |
| Max Allowable Coil Voltage | 6.5 VDC |
| Contact Resistance | ≤ 100 mΩ |
| Contact Rating | 10 A @ 250 VAC / 30 VDC |
| Dielectric Strength | 1500 VAC |
| Vibration Resistance | 10–55 Hz, 1.5 mm amplitude |
Tips for Using SMIH-05VDC-SL-A
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Use a flyback diode (e.g., 1N4007) across the coil — to protect microcontroller pins or transistor drivers from voltage spikes.
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Use a transistor driver (2N2222, BC547, or 2N3904) — don’t drive the relay coil directly from a microcontroller pin (coil draws 60–70 mA).
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Provide stable 5V supply — use a separate power line if your circuit draws high current.
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Avoid frequent switching — relays are mechanical and wear with constant operation.
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Respect contact limits — never exceed 10A / 250VAC; for inductive loads (motors), use snubber or MOV protection.
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Keep relay isolated from sensitive analog circuits — electromagnetic interference can affect readings.
Typical Applications
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Arduino / ESP32 / Raspberry Pi automation
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Smart home control (lights, fans, pumps)
-
Industrial PLC interface
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DIY power control modules
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Motor or solenoid switching
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Security alarm systems
-
Power relay boards (1/2/4/8 channel modules)
Quick Summary Table
| Parameter | Value |
|---|---|
| Model | SMIH-05VDC-SL-A |
| Coil Voltage | 5 V DC |
| Coil Current | ~70 mA |
| Contact Rating | 10 A @ 250 VAC / 30 VDC |
| Contact Type | SPDT (1C) |
| No. of Pins | 6 |
| Coil Power | 0.36 W |
| Operate Time | ≤10 ms |
| Release Time | ≤5 ms |
| Mounting | PCB |
| Dimensions | ~19 × 15.5 × 15 mm |
