Solid State Relay
Build a solid-state relay (SSR) using BT136 TRIAC. Controls AC loads without mechanical contacts, ideal for DIY electronics, automation, and hobby projects.
SSR circuit using TRIAC:
BT136 is a solid-state relay that can control AC loads without any noise. The BT136 TRIAC is a low-voltage DC input DC switch with low voltage and high reliability, fast and reliable operation.
LM340 Voltage Output Formula:
Vout = 5V (Fixed for LM340-5.0)
Recommended Capacitor Values:
Vout = 5V (fixed)
Vin ≥ 7V (for linear regulators like 7805)
5v power supply using 7805
A 5V voltage regulator is a necessary part that gives constant 5V output no matter what the input signal voltage may vary. It is extensively found in electronics circuits, Arduino and Raspberry Pi boards and any other embedded system to provide enough stable power supply to keep these devices safe and running effectively. It has two large formats: Linear (e.g. 7805) and Switching (e.g. LM2596 buck converter). Linear regulators are easy and easy to make and switching regulators are reasonably efficient. High current loads in the linear types may need a heat sink. Input voltage should be always at higher levels i.e. 5V, ideally 7-12V.
LM7805 regulator connection
| Input Voltage (V) | Output Voltage (V) | Regulator Type |
|---|---|---|
| 12V | 5V | 7805 (Linear) |
| 9V | 5V | 7805 (Linear) |
| 6V | 5V | LM2596 (Switching) |
Frequently Asked Questions - Solid State Relay:
What is BT136?
A TRIAC used for switching AC loads in solid state relay circuits.
Voltage requirement?
Control input typically 3–12V DC, AC load per TRIAC rating.
Can it switch high AC loads?
Yes, depending on BT136 current and voltage rating.
Silent operation?
Yes, SSRs have no mechanical contacts.
Applications?
Lamps, motors, heaters, home automation, DIY projects.
Beginner-friendly?
Yes, simple low-voltage control with AC isolation.
Do I need an opto-isolator?
Recommended for safe separation of AC and DC circuits.
PCB required?
Optional, can use breadboard for low-power prototypes.
Can it replace mechanical relay?
Yes, provides faster and longer-lasting AC switching.
AC load limitations?
Ensure load does not exceed TRIAC’s rated voltage/current.
