The FS1000A is basic RF transmitter than comes in at least two frequencies, 315 MHz and 433.92 MHz.

None of the devices tested are particularly well tuned and tuning also alters somewhat when attaching an antenna. The Gqrx image shown is one example FS1000A at 433.863 MHz with a 17cm antenna. On the same plot we can see a faint signal from another device which is exactly 433.92 MHz.

The 315 MHz transmitter is not legal where I live, however, due to the incompetence of one eBay seller I have one for testing.

These devices work fine using 3V3 or 5V for VCC and the digital input named DATA or ADAT or ADAT upside down works equally well at 3V3 for 3V3 VCC or 5V VCC.

The digital input floats at a around -0.8V when unconnected.