A Superregen Receiver for FM broadcast or Aircraft band AM reception Feb ; Revised October by Rick Andersen This is the receiver I was bragging about on the Radio index page — the receiver that is so sensitive it can hear the local oscillator inside a small transistor radio 30 – 50 feet away. Build one of these little gems and you will be able to hear aircraft pilots many miles away with nothing more than a 24″ whip antenna. The Superregenerative detector was popular, in its vacuum tube version, in the early days of VHF reception up through the late ‘s, early ’60s. After that, it was found in its transistorized version in simple kits from Radio Shack, etc. Though a lot of people haven’t even heard of it, and others think it’s obsolete, the fact is that the superregen is still around in specialized high-frequency applications. Our use of it here is a throwback to the old days when homebrew ‘supergennys’ were in vogue — as an extremely simple, yet extremely sensitive, broadband VHF receiver that will demodulate FM broadcast stations as well as AM aircraft band transmissions. In the circuit below, Q1 serves as the superregen detector. Now this configuration is a strange beast, if you’re only casually acquainted with transistor circuit design. First of all, in the original embodiment of this circuit, the signal was coupled into the collector circuit of the 2N NPN transistor; usually we connect the input to the base or emitter, and the collector is considered to be an “output”. Well it turns out that the high impedance of the LC tuned circuit, at the collector, makes it susceptible to outside influence, if we connect an antenna at that point
Electrical wiring of sensors
Emitter Source Connect the base to an output pin of the microcontroller, and the emitter to ground like so: Connect a motor and power supply Attach a DC motor to the collector of the transistor. Most motors will require more amperage than the microcontroller can supply, so you will need to add a separate power supply as well. If your motor runs on around 9V, you could use a 9V battery. A 5V motor might run on 4 AA batteries. The ground of the motor power supply should connect to the ground of the microcontroller, on the breadboard.
The Keyall HV kit allows the owner of a keyer with a low voltage positive (NPN or n-channel MOSFET) keying transistor to drive the vacuum tube transmitters and transceivers of yesteryear.
This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored.
It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc. The output waveforms can be both amplitude and frequency modulated. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground.
It also analyzes transistor’s characteristics such as voltage and gain. It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. Headphone amplifier is small enough to fit in Altoids tin box, and thanks to low power consumption may be supplied from a single 9V battery.
It’s small, power efficient, yet customizable through onboard 2 x 7 perfboard that can be used for connecting various sensors and connectors.
ITP Physical Computing
I have managed to destroy a few sensors in the process….. People have told me that when the NPN sensor blows it has a tendency to blow in an open state. People have told me that when the PNP sensor blows it has a tendency to blow in a closed state. Signal On When the sensor blows, malfunctions it usually will also take out the power supply. If you do mix the sensors, then the different common points on the PLC must be isolated from each other. This means that the commons are not connected internally to each other.
The BLX87 is an NPN power transistor made from silicon. The data sheet shows it can be used in environments with radio frequencies. Inspect transistors with JIS labeling. The 2SB is a PNP transistor type. The label will often read B, where the 2S is assumed. The data sheet shows it is used in low-frequency power amplifiers.
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OpenLab Seven Segment Display Board Hookup Guide
The items you will get, are on the Bill of Materials. Those you will NOT get, and must get on your own, separately! Thank you for your purchase of this nixie clock kit. The design is based around an AVR Mega88 microcontroller. It can drive 6 nixie tubes, and an optional dekatron.
Wiring NPN/PNP – Brainboxes – Ethernet, IO, & Serial Cards. Whether to use NPN or PNP depends on which direction you want the current to flow. A NPN sensor sinks current to drive the ED input to 0V. A PNP sensor sources current to drive the ED input to a positive voltage.
Calibrating The Speed Control Programming Instructions Calibrating the speed control Warning It is very important that the drive attached to the Digi-Lok be properly calibrated for its motor—with one exception. Calibrate the motor speed controller for use with the DLC. The objective is to optimize the response of the speed control to the DLC signal and to minimize any tendency by the speed control to independently attempt to regulate motor speed. Programming Mode Programming Instructions Programming Mode Programming can be done before the DLC is installed, or before it is connected to the speed controller, or after the entire system is set up.
Usually, it is more convenient to program the DLC before it is connected to the speed controller, because the motor will not then be running. The selected Load Response Number determines the rate at which the DLC output voltage is changed, for a given difference between set speed and actual speed. Page 30 Programming Instructions The governing equation is: The entire numerical speed setting entry has to be used in this equation.
Delete the decimal point, if present. The number of feedback pulses per revolution is known. The number of decimals displayed in Programming Mode tells which parameter is being displayed. One decimal point signifies SSF programming. Page 32 Programming Instructions If your application does not run properly, as evidenced by failure to lock into speed, you first need to check that shock loading is not occurring.
This is typically done by switching a voltage or current on or off. In some cases the output of the sensor is used to switch a load directly, completely eliminating the PLC. Typical outputs from sensors and inputs to PLCs are listed below in relative popularity.
How to Test Whether a Sensor has a PNP or NPN Type Output Using a Multi meter If you are replacing a 3 wire sensor which operates on DC voltage, it is important to know whether the sensor’s output is a PNP or NPN type.
There are two basic types of 3 wire proximity sensor applicable to certain types of PLC. Although some modern PLCs are designed with the ability to provide accessibility to easily switch the circuit connection between these two configuration, awareness on the distinction between these two types of standards is a must in order for the user to know which particular type of proximity sensor to use for a particular type of PLC. The following electrical diagrams illustrates the difference on the wiring connection between a PNP and an NPN proximity sensor when connected to a sinking and sourcing configured input Mitsubishi PLC.
The distinction between the wiring connection of Figure 1 from Figure 2 lies mainly on the electrical property of the NPN transistor and the PNP transistor, which pertains to the way both behave differently in an electrical circuit. Figure 2 clearly illustrates how this is achieved. The diagram in Figure 2 shows that to be able to make it suitable to the requirements of a negative logic circuit, the PLC was configured to conform to a source current input in order to make the intended circuit to work according to the conditions of a negative logic circuit.
Referring to the PLC electrical diagrams of Figure 1 and Figure 2, a manual push button switch is connected to the PLC input terminal X0 which when switched ON will cause to send one pulse action to the auxiliary relay coil M , which in turn will set and maintain M at ON condition. M will then eventually turn ON output coil Y0.
M also serves as a safety interlock contact in rung 3 that prevents any unnecessary activation of pulse M to avoid any unwanted resetting of M from stray object detection by the proximity sensor when the manual push button has not been switched ON yet. Subsequently, it follows then that for as long as M is initiated and maintained ON, the next step is to allow acknowledgement of input signal from the proximity sensor connected to the PLC input terminal X1 when it is activated by detecting objects, which will send one pulse signal to energize M , which will eventually reset M to turn OFF output coil Y0.
Another circuit distinctly different from what was featured in this article is the traditional wiring method, which is an alternative conventional approach outside the scope of this article discussed in my blog post Wiring Connection for a Three Wire Solid State DC Proximity Sensor Without using a PLC. E arn while you learn to become an Electrician Apprentice!
Digital circuits[ edit ] The TTL output stage is a rather complicated push—pull circuit known as a ‘totem pole output’ the transistors, diode, and resistor in the right-most slice of this TTL logic gate circuit. It sinks currents better than it sources current. A digital use of a push—pull configuration is the output of TTL and related families. The upper transistor is functioning as an active pull-up, in linear mode, while the lower transistor works digitally.
For this reason they are not capable of supplying as much current as they can sink typically 20 times less. Because of the way these circuits are drawn schematically, with two transistors stacked vertically, normally with a level shifting diode in between, they are called “totem pole” outputs.
The NPN collector pin has been bent backwards slightly and is placed behind the base pin. This is easily seen in the second image. Double check all track cuts again and your soldering for bridges!
The line should be replace the parentheses with angle brackets: Seems the HTML has loaded the code when copied with formatting stuff and breaks the compile. But as near as I can tell the only line that got broken is the include statement. However, I also posted it at http: Seems to run beautifully using the bit-banging code from a previous post, but I am wondering about the reed-switch setup.
I have a metal fabrication business that I can find a ton of uses for these cheap used motors. Heck, the one I got was new and I picked it up for 50 bucks. If you can tell me a bit more about the sensor, I might be able to help. I will update you on that in the near future. The speed sensor doohicky I spoke of earlier is an 80 tooth wheel rotating through an optical sensor opto interrupter that uses on 5v power.
Looking at most of the similar breakout board solutions available for arduino, they look identical, except those have 3 pins. Once I get that working, Is it possible to just take the rawSpindleSpeed reading and then divide it by 2, and have one of the arduino pins pulled to ground in relation to that number so that the MC gets the signal it wants for RPM control?
If i spin it by hand, I can get it up to about 30rpm and its fine. I can do it endlessly.