Combined module Soft Start (inrush current limiter) & DC Blocker (trap, filter) – assembled and tested PCB-v.2

 84.00 Incl. VAT
 70.00 Excl. VAT

Fully assembled and tested Soft start & DC Blocker/Filter/Trap combined module-v.2

In stock (can be backordered)


Sometimes a module for soft starting the big toroidal transformer (limiting the inrush current) along with blocking the DC component in the Mains is needed. And here is offered a combined Soft Start & DC Blocker module.

Basically it is a combination of two other my designs: soft start module and DC Blocker In deep description of both modules can be find in its corresponding pages. A simplified block-schematic is given below.

Block-schematic of the Combined Soft-start & DC Blocker module


As it can be seen from the title, this is the second iteration of the module. The differences here are the usage of monolithic AC/DC converter instead of the capacitive divider used in the first version and the migration to SMT parts, used in the Soft-start logic circuitry.

– Wide range of AC mains working voltages: 85 – 265V AC
– time delay for relay engagement: 3.5 sec.
– possibility to work with wide variety of toroidal transformers: 300 – 3000 VA
– current consumption with relay turned on ~ 100 mA

PCB for the schematic is with dimensions 110×100 mm.
PCB type: FR4 1.6 mm. Copper thickness: 70um (2oz). Surface finish – Nickel Gold (ENIG).
It is two-layer design with solder mask coating on both layers for best durability. Silk screen with parts layout is placed on the top of the PCB.

Note: As was stated above, the schematic is designed to work in wide range of AC Mains voltages thanks to the versatile Zettler ZP03SXX00WE series AC/DC converter but since there’s a difference in the values of the ballast resistors for 115 and 130V AC Mains voltages, please add this information in the comments during the process of checkout.

Soft start part of the module utilizes a 20A power Omron G4A-1A-E relay. DC Blocker uses large 47000uf electrolytic capacitors. The overall power that module can handle is approx. 3000VA.

PCB is populated with all possible paralleled resistors (9 pcs.) which form the series ballast resistor. This corresponds to the max. handled transformer power (approx. 3000 VA). In case your transformer is smaller than the mentioned above, contact us prior to purchase and the optimal resistor’s value will be picked up. Otherwise you will get the full resistors set and could tune it’s value by un-soldering (cutting) unneeded ones.

On the PCB are placed 3-pins connector for AC Mains input and AC Output connector with ability for attaching up to 3 consumers with independent Live, Neutral and Ground terminals.

What the buyer will receive:
The package will contain 1 pcs. Fully Assembled and tested PCB for Combined module Soft Start (inrush current limiter) & DC Blocker (trap, filter) – v.2.

The unit will be shipped with Priority AirMail Registered/DHL/FedEx (or equivalent courier service where applicable). The tracking number will be sent to the customer after shipment.

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Fully assembled and tested Soft start & DC Blocker/Filter/Trap combined module-v.2
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Additional information

Weight 0.51 kg