Radio LEDs

This article is based on another article that I published:

https://www.instructables.com/Radio-Bright-LED

The circuit on this article is a bit more complicated because it includes all of the five channels.

The transmitter range is a lot longer than 20 cm:

My friend published an article on this website:

https://hackaday.io/page/10304-antenna-remote-control

This article about an RF remote control kit from Oatley Electronics (https://oatleyelectronics.com).

The kit included a relay driver that you do not need for this circuit because you are not controlling high current loads.

I purchased the receiver board on eBay and borrowed the transmitter from my friend.

You must not forget that you need to active the board by pressing on the small button that you see on your right.

Side 2:

Step 1: Design the Circuit

I have drawn the circuit via online Easy EDA software:

The positive ends of each of the four LEDs must be connected to each of the four RX480E channel outputs. You need a separate resistor pair (two 1,000 ohm resistors in parallel) for the big blue LED because each of the four LEDs were pulling enough current from the 1 kohm resistor that the potential difference across the big LED was not sufficient enough for the big blue to turn ON at the same time with the small LED (refer to video - the big LED is ON because I did use a separate resistor pair for this LED).

Step 2: Make the Circuit

Making circuit requires basic soldering skills. I would not say that soldering this circuit is for beginners.

I did not have additional two 1 kohm (1,000 ohms) in stock. Thus I used two 1,200 ohms resistors. You do not need the high power resistors that I used for this circuit. I used what I had in stock.

Step 3: Testing

You can see the small LED turning ON in the close up testing videos:

Video 2:

Conclusion

This is a cheap solution for a remote controlled toy. You can connect the RX480E outputs to transistor inputs (BJT or MOSFETs) and make a motor move. Thus you can make toy:

- drones, 

- cars,

- planes,

- helicopters,

- or boats

Infrared LED

Many years ago when I was designing an infrared camera slave pointing system the cost of an infrared receiver IC (integrated circuit) was about $7. This IC was TTL (Transistor Transistor Logic) with three pins. Power, Output and Ground. Then the price increased to about $8 which when I actually purchased this IC in late 2002. I also obtained a copy of the datasheet from the electronics store. However, the printing was very low quality and this is why I could not read the pins properly. I must have made a mistake with the pins and partially burned this IC. The IC was receiving the infra red signal well. However, it had a weak output drive because I have partially burned it.

Nowadays the cost is only about $3. This make this ICs appropriate for cheap circuits.

Here is the video of the circuit working:

First I read the following articles about old fashioned transistor amplifier circuits that can be used to amplify signals from infrared sensors:

https://www.instructables.com/id/Transistor-Sensor-Amplifier/

https://www.instructables.com/id/Recycled-Transistor-Amplifier/

I designed the circuit with the ZD1953 IC and a simple PNP BJT (Bipolar Junction Transistor) inverter.

Step 1: Make the Circuit

Two transistors were placed in parallel to improve reliability and increase device life time. However, using a second transistor is not necessary. The circuit can still work well with one transistor. You also might not need a second 1 kohm resistor either. The two 1 kohm resistors are connected in series to reduce the maximum transistor base current.

From top to bottom the pin layout is:

1. Output (connected to 1 kohm resistor)

2. Ground (blue wire)

3. 5 V Power Supply for TTL (red wire)

The PNP transistor collector is connected to four LEDs in parallel with the blue 100 ohm resistor. The voltage potential is:

VoMax = Vled + Vr

= 2 V + 100 ohms * 25 mA = 4.5 V

There are four LEDs. Each LED will receiver about 6.25 mA of current. Those LEDs are made to consume 5 mA.

Suppose we raise the power supply to 6 V:

VoMax = Vled + Vr

= 2 V + 100 ohms * 40 mA = 6 V

Each LED will receive about 10 mA of current.

I placed the circuit in a plastic container because I did not want to pay for the box.

Step 2: Testing

I used my infrared transmitter to keep the LEDs ON long enough so that I could take a photo:

You can see my transmitter sending the signal to the infrared sensor:

Three Transistor Amplifier

This article shows DC simple three transistor amplifier.

Applications include:

- sensor amplification (biased or non biased),

- current amplification (amplification of current sources - transistors)

This circuit is useful for continuing a cascade of current amplification.

You can see the circuit working as touch switch this video at just 1 V:

Step 1: Design the Circuit

I drawn the circuit via https://easyeda.com online software:

A 1 kohm resistor is useful for limiting the transistor base current. Increasing the Rb value will reduce the circuit gain but will also reduce the circuit current consumption and reduce the chances of power supply oscillations. However, the video is showing that the circuit is working well.

Step 2: Make the Circuit

I did not use a soldering iron. I twisted the wires with pliers.

You can make this circuit on a piece of cardboard or plastic.

I used blue tack to attach the circuit to box. However, the circuit might still move if you shake the box fast. Thus better use screws, nuts and bolts. Also, you should secure wires to matrix board with cable ties or 1 mm metal wire to prevent wire damage due to opening and closing of the box.