Highlights:

• All New Revised Edition With Exclusive Custom Made 10A Anti Vandal LED Ring Latching Switch
• Now Features FR4 grade glass-reinforced epoxy PC Board with Gold Emmersion and High Grade Black Soldermasking
• PCB Copper Foil is 2 oz for High Current Handling
• High Quality Parts Used throughout : Nichicon FW  / EPCOS X2 Capacitors
• Onboard Fuse protection uses New Fuse Holder with Protection Cover
• LeOne 30A Relay

Description:
The linear power supplies normally used in Audio Power amplifiers draw a very large but brief current when they are first turned on. This large current can eventually damage some of the components as well as produce a 'thump' in the speaker. 
This soft start circuit can be installed in the mains supply to an Audio Power Amplifier to address this problem. It will limit the initial current flow by using four robust NTC thermistors in series with the mains supply. During the turn-on period when the mains current flows through these thermistors they may heat up - this is normal and not an indication of any problems with the circuit.

A bridge rectifier circuit on the pcb draws power from the mains AC via input capacitors and produces a DC voltage which is used to charge up the three filter capacitors . An LED is placed across these capacitors to indicate that these capacitors are charging and will stay lit even after the capacitors are fully charged. Hence the LED illuminates when the circuit is functioning normally. When the voltage on the three filter capacitors reaches a threshold of 24V it is sufficient to activate the relay which closes a pair of heavy duty contacts across the NTC thermistors. The mains current can now flow directly through the relay contacts to the external circuit instead of through the NTC thermistors. This allows the external circuit to achieve full current flow. It takes approximately 3 seconds for the three filter capacitors to charge up and activate the relay. For these 3 seconds the current to the external circuit is limited and a Soft Start is achieved. When the mains is turned off the three filter capacitors take a couple of seconds to discharge so you will see a delay before the LED turns off.

A protection diode (D5) is installed across the relay solenoid to prevent any damage to the circuit from voltage spikes when the relay turns on and off and a pair of Zener diodes (DZ1, 2) are used to clamp the voltage across the relay solenoid at a maximum of 24V.

A safety fuse is provided on the board. Depending on your application you may choose to replace it with a value better suited to protect the external circuit; it should be a mains rated type 2AG (5mm x 15mm).
If you are confident to make your own changes to the board you can adjust the time delay for the Soft start to better suit your application by changing the value of the capacitors C5 and C6. A larger value will reduce the initial delay and a smaller value will increase the initial delay. If the value is too small the circuit may fail to operate correctly and the relay will not close so some experimentation may be required. The circuit is designed for a 220V - 240V mains supply.

Specifications:

• PCB size : 90mm x 60mm
• PCB thickness : 2mm
• Mounting Holes C-C Distance : 83mm x 53mm 
• Max Component Height :20mm
• Recommended Max current Handling : 1600 watts
• Delay : 3 secs

Switch Specifications:

• Rating : 10 A 230V
• Indicator : LED Ring Light
• Size: 19mm Diameter
• Mounting Hole Size : 19.5mm

Caution: This board requires a high Voltage to be carried to the Device's Front panel for switching purposes,so it is adviced to take utmost care while doing the wiring 

Whats Included:

1. Main Soft Start Board - 1 Pc
2. Insulated Female disconnects - 4 Pcs
3. M3 type Brass PCB mounts 5mmX8mm - 4 Pcs
4. M3 Screws - 4 Pcs
5. Exclusive Latching Type 10A Anti Vandal Latching Switch - 1PC

Connections: