OpenSmart ASK Sender

Questionable RF Sender For *ASK* Modulation With PCB Antenna

The company OpenSmart released this ASK sender with an unmarked transmitter chip and poor documentation.

The sender is sold as a kit together with a receiver board and is available in separate versions for 315MHz (US) and 433MHz (Europe).

The actual sender is located on a separate and much smaller board that is soldered onto a bigger bpard which only purpose apparently is to provide a PCB antenna.

While PCB antennas certainly are convenient and compact, they are not efficient, limiting the distance that can be reached. During build time and testing, make sure you do not touch the antenna or hold the breakout board in a way that covers the antenna.

The way how the transmitter board is piggy-backed into a relatively huge antenna board makes this solution the most clumsy of all reviewed.

Apparently, the company OpenSmart uses these modules in various combinations together with other boards to make them wirelessly controllable. For example, OpenSmart also sells wireless joystick and sensor boards that use the same fundamental sender and receiver boards.

The company OpenSmart advertises this board as “Long-Range Transmitter” and even as “LORA Board”. This board is neither able to transmit RF signals over long distances nor does it implement LoRa modulation. It is simply a cheap and very simple ASK transmitter.

The RF frequency of the board on is printed on the front side. The 433MHz version uses blue boards, and the 315MHz version uses red boards.

Technical Data

Item Value
Voltage 4-12V
Frequency 433MHz or 315MHz
Working Current 40mA
Output Power 27dBm/500mW at 12V
Modulation Mode AM (OOK)
Transmission Rate <4.8 Kbps
Transmission Distance <50m at 5V
Size 24x30x7mm

With input voltages below 5V, the data transmission becomes unreliable. When powered with 12V, the claimed output power of 27dBm/500mW seems to be unrealistically high and demands further testing.


The board comes with three pins.

Pin Tag Description
1 SIG Data In
2 VCC 5V
3 GND negative pole


The vendor suggests to use the VirtualWire software library.


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(content created Apr 18, 2024)