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Ramsey Electronics manual Using the FM10A Within the Home, Power Supply Considerations

Models: FM10A

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USING THE FM10A WITHIN THE HOME

A most practical use for the FM10A would be to connect it to the main stereo system within a large home so that whatever is playing on the main system can also be tuned-in on portable FM radios in other rooms, the garage or out in the yard.

This connection consists of using shielded audio cables to connect the auxiliary "line audio" output of your cassette deck, CD player or other stereo device to the audio inputs of the FM10A. Consult the literature that came with your stereo equipment.

Even if you intend only this limited convenience use of the FM10A for your own home and family, it is still your responsibility, in accord with Part 15 of the FCC Rules, to ensure that this operation does not cause interference to your neighbors.

POWER SUPPLY CONSIDERATIONS

The FM10A is designed to operate from a single 9-volt battery mounted on the PC board. For prolonged operations, note from the schematic diagram that replacing R8 with a jumper wire will permit operation from a 1.5V or 3.0V DC source such as D cells. Diodes D1, D2 and D3 regulate the voltage to U1 at 2.1 volts. Note, however that reduced voltage will also affect the collector voltage and therefore the output power of Q1.

Whether an alternative AC adapter can be used depends on the quality of the adapter and its ability to suppress unwanted AC-line hum. Various plug- in adapters and power supplies in the 6 to 12 volt range may be tried, but make sure the unit has DC output (positive tip) and is not merely a transformer relying on rectifier circuitry within the device for which it was originally supplied as an accessory.

L.E.D. "POWER ON" INDICATOR

Since the transmitter consumes power and emits RF whenever it is turned on, a visual "on the air" indicator is desirable and is a fun enhancement of your completed kit. If you are designing the FM10A setup for use by youngsters, a flashing indicator is easily provided using our BL-1 "LED Blinky" kit. Voltage for a standard LED is easily taken from the unused top terminals of S1. The inner pin nearest the red lead of the battery cable is the +9 volt pin. The ground can be taken from the black battery terminal, or the case of any of the jacks, but it CANNOT be the antenna. This positive DC must be connected to the anode (longer wire) of the LED. Use a 1K resistor in series with either wire of the LED. The cathode lead is connected to the

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Ramsey Electronics manual Using the FM10A Within the Home, Power Supply Considerations, D. Power on Indicator
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FM10A specifications

The Ramsey Electronics FM10A is a compact and efficient FM transmitter tailored for hobbyists, educators, and anyone with a passion for creating their own radio broadcast. This device stands out in the world of electronics due to its user-friendly design and array of features that make it an ideal starting point for both beginners and experienced users.

One of the main characteristics of the FM10A is its simplicity in setup and operation. Users can quickly assemble the kit without the need for advanced soldering skills, making it accessible to a broader audience. The transmitter operates in the FM band, allowing for high-quality broadcasts with minimal distortion. Its frequency stability is maintained through a PLL (Phase-Locked Loop) technology, ensuring that the transmitted frequency remains consistent throughout its operation.

The FM10A features adjustable transmission power, allowing users to customize their broadcast range. With a maximum range of approximately one mile under optimal conditions, this device is versatile enough for personal use, small events, or classroom demonstrations. Additionally, the transmitter is equipped with an audio input for connecting various media sources such as smartphones, computers, or other audio devices. This flexibility makes it suitable for a range of applications, from playing music to broadcasting educational content.

Another notable feature is its compact design, which makes the FM10A easy to transport and set up in different locations. The device is powered by a standard 12V supply, which is widely available, making it convenient for users at home or on the go. The lightweight nature of the unit further enhances its portability, enabling users to take their radio broadcasts anywhere.

The FM10A also includes an LED power indicator and a built-in antenna for straightforward operation. Users can enhance their transmitting range by adding an external antenna, providing further customization based on specific needs. The kit comes with comprehensive instructions to guide even those new to radio transmission through each step of assembly and operation.

In addition to its engaging technical features, the FM10A serves as an educational tool. Users can learn about radio frequency technology, electromagnetic theories, and audio broadcasting principles, making it an excellent addition to any STEM program. Overall, the Ramsey Electronics FM10A is a stand-out choice for anyone looking to delve into the world of FM transmission with a robust, user-friendly device that doesn't compromise on quality and functionality.