Here is a Receiver Schematic that works on FM and AM band. A FM receiver can be built easily using only a single chip CXA1019. This circuit has been following with a PCB.

FM/AM receiver operates on a DC voltage of 6 volts or uses four pieces of AA batteries. For other component specifications can be seen on the list of components on the bottom of the article.

CXA1019 FM receiver schematic is quite easy to build because it uses a small number of components with low current consumption is 5.3 mA at 3V Vcc. However, it’s an AF amplifier with large output of about 500mW at 8? load impedance.

FM Receiver Schematic – PCB

CXA1019 FM Receiver Schematic

CXA1019 FM Receiver-PCB Top

PCB Dimension : width=7.95 cm, Height=4.90 cm

CXA1019 FM Receiver-PCB Bottom

CXA1019 FM Receiver Part List

CXA1019 FM Receiver Part List

XCA1019 FM Receiver Parts

For those who are beginners this is an exciting electronic project to add to the experience, namely how to make an FM/AM radio using a receiver schematic.

See also: Emergency Radio Circuit - Transistor FM Receiver Circuit

In the world of RF, the antenna is one system that is very important because the antenna can determine how far the signal goes. The antenna is an element which radiates the signal. Electromagnetic field signals can be polarized in a circular, vertical, and horizontal. Here is the FM broadcast antenna is circularly polarized, is used in FM transmitter in the frequency range 88-108 MHz.

FM Broadcast Antenna and Material Specifications

Antenna made of copper pipe (pipe AC), the reasons for using these materials are easy to create circular shapes. Diameter copper pipe is 0.5 “.

Circular FM Broadcast Antenna

This antenna has a gain of about -1.5 dB (isotropic dipole). Increasing the amount of gains made through stacks of more than one antenna. More and more antennas are stacked, it will increase the amount of gain antennas, so that will be able to double the ERP (Emmition Radiating Power).

Antenna Dimensions

For the antenna size can be seen on circular FM broadcast antenna diagram below:

Circular FM Broadcast Antenna Diagram

Signal amplification

Gain is based on the antenna gain in Decible (dB). ERP is calculated by multiplying the power of the transmitter with antenna gain. When four antennas stacked estimated to have a 3:12 dB gain, 5.12 dB for six antennas, and 6.40 dB for eight antennas. (3dB= 2,  e.g. Antenna Gain for eight antennas =6.40/3 x 2 = 4.26)

ERP = Transmitter Power (Watt) x Antenna gain.

Please learn more from various sources to understand this type of FM broadcast antenna.

See also: FM Radio Transmitter Circuit – iTrip FM Transmitter Review

Here’s a Wireless FM transmitter circuit powered from USB ports that could be used to play audio files on a standard VHF FM radio. The transmitter circuit use no coils that have to be wound. The wireless FM transmitter can be used to listen to your own music throughout your home. When this wireless FM transmitter used in the car, there is no need for a separate input to the car stereo to play back the music files from your MP3 player.

This wireless FM transmitter use a chip made by Maxim Integrated Products, the MAX2606 [1]. This IC from the MAX2605-MAX2609 series has been specifically designed for low-noise RF applications with a fixed frequency. The VCO (Voltage Controlled Oscillator) in this IC uses a Colpitts oscillator circuit. The variable-capacitance (varicap) diode and feedback capacitors for the tuning have also been integrated on this chip, so that you only need an external inductor to fix the central oscillator frequency.

USB Wireless FM Transmitter

Wireless FM Transmitter Circuit Diagram

Based on wireless FM transmitter circuit schematic, it is possible to fine-tune the frequency by varying the voltage to the varicap. Not much is demanded of the inductor, a type with a relatively low Q factor (35 to 40) is sufficient according to Maxim. The supply voltage to the IC should be between 2.7 and 5.5 V, the current consumption is between 2 and 4 mA. With values like these it seemed a good idea to supply the wireless FM transmitter circuit with power from a USB port.

USB Wireless FM Transmitter Schematic

A common-mode choke is connected in series with the USB connections in order to avoid interference between the wireless FM transmitter circuit and the PC supply. There is not much else to the circuit. The stereo signal connected to K1 is combined via R1 and R2 and is then passed via volume control P1 to the Tune input of IC1, where it causes the carrier wave to be frequency modulated. Filter R6/C7 is used to restrict the bandwidth of the audio signal. The frequency setting of the wireless FM transmitter (across the whole VHF FM broadcast band) is done with P2, which is connected to the 5 V supply voltage.

Wireless  FM Transmitter Parts List

Resistors (all SMD 0805)
R1,R2 = 22k?
R3 = 4k?7
R4,R5 = 1k?
R6 = 270?
P1 = 10k? preset, SMD (TS53YJ103MR10 Vishay Sfernice, Farnell # 1557933)
P2 = 100k? preset, SMD(TS53YJ104MR10 Vishay Sfernice, Farnell # 1557934)
Capacitors (all SMD 0805)
C1,C2,C5 = 4?F7 10V
C3,C8 = 100nF
C4,C7 = 2nF2
C6 = 470nF
Inductors
L1 = 390nF, SMD 1206 (LQH31HNR39K03L Murata, Farnell # 1515418)
L2 = 2200? @ 100MHz, SMD, common-mode choke, 1206 type(DLW31SN222SQ2L Murata, Farnell #1515599)
Semiconductors
IC1 = MAX2606EUT+, SMD SOT23-6 (Maxim Integrated Products)
Miscellaneous
K1 = 3.5mm stereo audio jack SMD (SJ1-3513-SMT
CUI Inc, DIGI-Key # CP1-3513SJCT-ND)
K2 = 5-pin header (only required in combination with 090305-I pre-emphasis circuit)
K3 = USB connector type A, SMD (2410 07 Lumberg, Farnell # 1308875)

USB Powered Wireless FM Transmitter PCB

The wireless FM transmitter PCB designed uses resistors and capacitors with 0805 SMD packaging. The size of the board is only 41.2 x 17.9 mm, which is practically dongle-sized. For the aerial an almost straight copper track has been placed at the edge of the board. In practice we achieved a range of about 6 metres (18 feet) with this.

There is also room for a 5-way SIL header on the board. Here we find the inputs to the 3.5 mm jack plug, the input to P1 and the supply voltage. The latter permits the wireless FM transmitter circuit to be powered independently from the mains supply. Inductor L1 in the prototype is a type made by Murata that has a fairly high Q factor: minimum 60 at 100 MHz.

USB Wireless FM Transmitter PCB

Measurements with an RF analyzer showed that the third harmonic had a strong presence in the transmitted spectrum (about 10 dB below the fundamental frequency). This should really have been much lower. With a low-impedance source connected to both inputs the bandwidth varies from 13.1 kHz (P1 at maximum) to 57 kHz (with the wiper of P1 set to 1/10). Author: Mathieu Coustans, Elektor Magazine, 2009 – USB Wireless FM Transmitter.

See also:  FM Antenna Diagram – RF Wireless Circuit

Here’s simple FM receiver circuit for a simple super-regenerative FM radio. It is sensitive, selective, and has enough audio drive for an earphone. These designs generally have low component counts, however the design or my construction have been far from simple.

FM Receiver Circuit Diagram

Because the FM receiver is a super-regenerative design, component layout can be very important. The tuning capacitor, C3, has three leads. Only the outer two leads are used; the middle lead of C3 is not connected. Arrange L1 fairly close to C3, but keep it away from where your hand will be. If your hand is too close to L1 while you tune the FM receiver, it will make tuning very difficult.

One Transistor FM Receiver Circuit Schematic

FM Receiver Circuit – Winding L1

L1 sets the frequency of the radio, acts as the antenna of the FM receiver, and is the primary adjustment for super-regeneration. Although it has many important jobs, it is easy to construct. Get any cylindrical object that is just under 1/2 inch (13 mm) in diameter. I used a thick pencil from my son’s grade school class, but a magic marker or large drill bit work just fine. #20 bare solid wire works the best, but any wire that holds its shape will do. Wind 6 turns tightly, side-by-side, on the cylinder, then slip the wire off.

Spread the windings apart from each other so the whole coil is just under an inch (2.5 cm) long. Find the midpoint and solder a small wire for C2 there. Mount the ends of the wire on your circuit board keeping some clearance between the coil and the FM receiver circuit board.

FM Receiver

FM Receiver Circuit – A tuning knob for C3

C3 does not come with a knob and I have not found a source. A knob is important to keep your hand away from the capacitor and coil when you tune in stations. The solution is to use a #4 nylon screw. Twist the nylon screw into the threads of the C3 tuning handle. The #4 screw is the wrong thread pitch and will jam (bind) in the threads. This is what you want to happen. Tighten the screw just enough so it stays put as you tune the capacitor. The resulting arrangement works quite well.

FM Receiver Circuit – Adjustment

If the radio is wired correctly, there are three possible things you can hear when you turn it on: 1) a radio station, 2) a rushing noise, 3) a squeal, and 4) nothing. If you got a radio station, you are in good shape. Use another FM rceiver to see where you are on the FM band. You can change the tuning range of C3 by squeezing L1 or change C1. If you hear a rushing noise, you will probably be able to tune in a station.

Try the tuning control and see what you get. If you hear a squeal or hear nothing, then the circuit is oscillating too little or too much. Try spreading or compressing L1. Double check your connections. If you don’t make any progress, then you need to change R4. Replace R4 with a 20K or larger potentiometer (up to 50K). A trimmer potentiometer is best. Adjust R4 until you can reliably tune in stations. Once the circuit is working, you can remove the potentiometer, measure its value, and replace it with a fixed resistor. Some people might want to build the set from the start with a trimmer potentiometer in place (e.g., Mouser 569-72PM-25K).  Source: Build A One Transistor FM Receiver.

See also: Transistor FM Transmitter MP3 Circuit – VHF Radio FM Transmitter Circuit

Crystal Emergency Radio requires no power supply to operate because it uses energy from the signals it receives. Performance is – like one should expect – poor. Nevertheless, with a good antenna and proper ground, it shouldn’t be too difficult to tune to a strong AM station.

While this emergency crystal radio circuit is very simple, many points should be observed. The variable capacitor is relatively hard to get in a store these days, so your best bet to find one could be a junked AM receiver. Connect the case to the antenna and the central rod to ground. Otherwise, you’ll de-tune the circuit every time you touch the capacitor.

Emergency Radio

Emergency Radio Circuit

Next comes the coil. Originally, 60-80 turn air core coils of large diameter (10cm) were used. A less bulky alternative could be 30 turns of enamel-coated magnet wire wound on a ferrite rod. It works for me, at least.

Detection and demodulation of the signal is done by a germanium diode. In the US, 1N34 seems to be very popular. Here in Europe, AA119 is more common and offers similar performance.

Crystal Emergency Radio Circuit

Finally, you’ll need high-impedance headphones. These are also quite rare. Ordinary Walkman phones won’t work directly. Add an audio output transformer to drive them or build a small amplifier like shown on the next page.

Problems:
To hear anything, you’ll need a very long antenna. Use any hookup wire at least a few meters in length. Make sure that no power lines are nearby! A good ground is also vital, like a cold water pipe. Otherwise, plant a metal rod as deeply in the ground as possible and it should work well.

Possible uses:
In these times of incredible advance in technology, such a simplistic receiver doesn’t seem to have any real use at all. It’s a nice project for the more nostalgic types, though. Since crystal emergency radio no power is required for operation, having such a receiver could prove handy in an emergency situation or just to hear the news when you’re out in the woods backpacking.

Amplified Crystal Emergency Radio

An improved crystal emergency radio with a two-stage audio amplifier. The 2N3904 (or any other general-purpose NPN) acts as a preamplifier while the LM386 boosts the signal high enough to drive low impedance Walkman headphones or perhaps even a small speaker.

Crystal Emergency Radio Amplifier Circuit

Crystal Emergency Radio Pros and Cons

Problems:
The same rules that we’ve already been through at the previous circuit above.

Possible uses:
Make a real AM receiver! With a decent antenna and good ground you should be able to catch a station or two. A 12-turn air core coil 5mm in diameter should get you somewhere between 5 and 15 Mhz, for example. You might also experiment with different coils for other band with crystal emergency radio.

See also: RC Radio Circuit – RF Wireless Circuit