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CORE TYPE CURRENT BALUNHighly recommended. This is a very low loss balun and ideal for use with a tuner.This balun works by controlling currents. THERE IS NO TRANSFORMER ACTION. The two windings must be in the same sense (dots at the same end). The magnetic fields of opposing balanced working currents will cancel each other out and so present very little impedance (other than the resistance of the wires) to these currents. On the other hand, common mode currents will produce a mutually inductive magnetic field and face a high impedance.This means the more turns the better, up to a point. In this case, the windings are a transmission line that has losses but these are much lower than the losses transfering energy from one winding to another through a core.Design considerations are really very minimal. Since the losses of balanced lines are low compared to coax, you aren't losing much except for the resistance of the wires which is very low compared to radiating resistance anyway.The current balun shown here, wound around a steel bolt, is probably a little crude but why not? Steel or iron is not normally used for RF because there are too many eddys making it too inefficient for transformers. In this application, since there is no magnetic effect for the desired currents, it doesn't matter. For common mode currents on the other hand, inefficiency is an advantage. Not only is a high impedance presented to common mode currents, the energy from them is absorbed by the bolt.
I was about to start the experiment using these generic 433 MHz radio transmitter and receiver,
I'd like to hear if someone here has a second opinion.
The data pin of the receiver never shown any difference in voltage whether or not the transmitter was powered up. So I think I'll just replace them with another model.
1pcs STX882 433MHz ASK Wireless RF Transmitter Module1pcs SRX882 433MHz ASK Wireless RF Receiver Module)2pcs SW433-TH32DN (433MHz Nickel Plated Spring Antenna)STX882 is a ASK transmitter module with small size, ultra high power, low harmonics. With high stability, it can be achieved at 50mW power when the voltage is 3.6V, it is the maximumransmitter power module under the the same voltage in the market. Data port of the module can be connected to the microcontroller directly, make wireless product development and production more convenient.Features:- Frequency Range: 433/315 MHZ- ASK modulation mode- Small volume low self radiation- High-power long-range- Frequency stability- Various international testing standardsSRX882 ASK Wireless Remote Control----------------------------------------------------Superheterodyne Receiver ModuleSRX882 is a superheterodyne receiver with micro power and strong driving force, is supplementary STX882 / STX888 module. Data port of the module can be connected to the microcontroller directly, make wireless product development and production more convenient.Features:- Frequency Range: 433/315 MHZ- ASK /OOK modulation mode- Super anti-power interference- Low-power sleep less than 1uA- Low self radiation- Small size- Frequency stability and reliability- Various international testing standards
I want the voltmeter shows 0 when the transmitter is off. This can be done by changing the voltage reference from ground to 1.7V, which can be achieved using a potentiometer as voltage divider. The measurement would then have a range from 0 to around 200 mV.
Did you wrap the power supply / battery in aluminium?