TSA5532 Tuner Modules from PC TV Cards

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Some of the previous posts show methods of generating analog video with microcontrollers and RF modulation of it using ready made modules. Analog video is no longer in use in most parts of the world. TV tuner cards for analog signals are no longer manufactured and old ones are difficult or impossible to install on newer computers because there are no drivers. Despite this, analog video capture devices are cheap and widely available. Most are USB dongles, with video and audio inputs, no tuner.

Since I had some old TV tuner cards that were no longer compatible with my PC or had poor performance, I decided to take the tuners out of them. To my surprise, different tuners from different manufacturers looked pretty much the same on the inside. All of them used the same integrated circuits. The tuners I found are actually complete receivers, with included demodulator. This means you can get analog audio and video straight from the module pins. There are also modules with FM support, with stereo decoder.

In the photo below, you can see two tuners. The top one has FM radio support. You can see that it's similar to the other, but the rightmost compartment has some additional filters for FM IF.

Tuners from TV cards
Tuners from TV cards

USB Power Supply for Breadboard

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Breadboards are very useful for quickly building electronic circuits. But these circuits require power. The popular breadboard power supply you will find on the market is powered from more than 8 V by an AC-DC adapter. They can provide both 5V and 3.3V from linear 1117 regulators. These regulators can supply a maximum of 800mA, but because they work in linear mode and the PCB is not well built for heat dissipation, the current you can draw from such a device is very limited.

While trying to interface a gas sensor and a TV card tuner to an Arduino, I found that I had troubles powering them. Each of the mentioned devices need about 200mA. Both Arduino and the breadboard power supply use linear voltage regulators to provide 5V. I tried to use the breadboard power supply, but the regulator became hot immediately. Being fed with 12V, the 1117 regulator needed to dissipate (12 - 5) x 0.2 = 1.4 W. That's a lot for its small package.

I needed a better power supply. And I want it for breadboard projects. USB seems to be a pretty good power source, being able to provide at least 500mA. So I designed my own power supply. Since is USB powered, I thought it would be a good idea to have an USB port where I could plug development boards, without needing another computer USB port.

USB Power Supply for Breadboard

Program Arduino Pro Mini with CH341A dongle

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Arduino Pro Mini is a development board based on ATmega168 or ATmega328 microcontroller. Unlike other members of the Arduino family, this board does not have an USB port for PC connection. To program it, you need an USB to serial TTL converter. There are many choices here, and the Arduino Pro Mini has a pinheader port that matches the pinout of FTDI USB serial breakout boards. ATmega MCU doesn't need all serial port pins. It requires serial data pins RxD and TxD and also DTR, which is connected to reset pin.

CH340 is another USB serial interface. It can be found at the core of the cheapest USB serial adapters, but these dongles are difficult to connect to Arduino because there is no power pin and no exposed DTR pin. The power pins on the CH340 USB breakout board are used with jumpers to select voltage levels (3.3V or 5V).

CH341A is a complex interface chip which adds parallel, I2C or SPI interface. It is used by memory programmers. However, by setting a jumper, it works as an usual USB to serial adapter. I will be using here a popular device based on CH341A, the black MiniProgrammer, to program an Arduino Pro Mini compatible board.
Program Arduino Pro Mini with CH341A dongle

Measure RPM with Slotted Optical Switch

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Building an RPM counter is very easy with an optical switch and a way of counting pulses generated by the switch. A microcontroller, a frequency meter and even a logic analyzer can be used for this. Here, I will be using the cheapest and popular method: an Arduino. Optical switches are devices made of an emitter LED, usually infrared type and a receiver diode. Between the IR emitting LED and the receiver there is a slot. An opaque piece can pass through this slot and block IR beam. This will be detected by the receiver diode and its output will change state.

The piece that will block IR light will be a flange with a slot (a cutout area from the disc). When this passes through the switch's slot, the light reaches the receiver diode. Therefore, rotations are translated into a digital signal with a constant duty factor, dependant on flange configuration. The frequency of this signal needs to be measured and converted into RPM.

775 motor fitted with optical switch
775 motor fitted with optical switch

I2C Analog TV Modulator controlled by Arduino

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Analog video is getting replaced by digital signals which provide better resolution and picture without noise or interference. But, analog video signal is easy to generate with simple hardware and then it can be FM modulated for broadcasting over a wire. I2C controlled RF modulators are common modules in obsolete VCRs and set top boxes. Most of them cover the entire UHF band and support multistandard sound carrier frequencies. Once taken out of its device, the modulator needs a microcontroller to set up its frequency and other parameters.

Using an Arduino board with LCD and keypad shield a full featured modulator can be built. Arduino can be used to generate video too, but a single board can't use I2C and generate video in the same sketch. You'll need different boards if that's what you want to do.

I used for this project a Samsung RMUP74055AD modulator with MBS74T1AEF controller. Some searching reveals the same IC is also used by Tena TNF0170U722 modulator. Some datasheets will come up too, if you search for them. Anyway, these modulators are 5V devices.

RMUP74055AD UHF RF modulator
RMUP74055AD UHF RF modulator

Arduino Thermometer with... TV Output

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Analog video is getting replaced by digital signals which provide better resolution and picture without noise or interference. Although receivers for digital signals are cheap and popular, devices for generating such signals are expensive and intended for professional use only. On the other hand, analog video is easy to generate with simple hardware. You can even broadcast it over RF (on wire, not on air) with common modulators (standalone devices or modules from video game consoles, set top boxes, VCRs etc.).

An easy way to generate video signal is by using a microcontroller and some resistors. I'll use for this purpose an Arduino board (ATmega 328p) with the TVout library. The video signal is of low resolution and black&white. But it can be used to display data on a TV screen. If you no longer own a TV with analog video input, an USB capture card can be used. TVout library is interrupt based, therefore will interfere with some of other interrupt dependent microcontroller features.

Thermometer with TV Output
Thermometer with TV Output