Latest Projects in Digital Electronics

1.Three in One Tone Generator

         Various tone generator circuit produces three different type of sound according to input three different logic levels (i.e. 0&1, 1&0 and 1&1).

Circuit description of One Tone Generator

         This circuit is designed around digital IC 7400 which is NAND gate. The working of the circuit is like the working principle of oscillator circuit, where frequency depends
upon capacitors C₁ and C₂. The duty cycle of this circuit is 50%. The output is given to power amplifier circuit which further drive loudspeaker or head phone. For low frequency value of capacitor C₁ and C₂ must be high and vice-versa.

2.Multi-Mode Running light

         Running light based project is very interesting and one of the most made project. We use this type of project in many ceremony. Here is a unique project “Multi-Mode running-light” in the series of LED based project because it can operate in three different modes. 

Circuit description of Multi-Mode Running Light

        The whole circuit multi mode running light is designed and fabricated around timer IC and BCD UP-DOWN counter IC.

IC₁ and IC₂ is used to generate vary low and low frequency square wave respectively where output of IC₁ is connected to different point (SW₁) and is used when running light is working in differential modes and output of IC₂ is connected to input of BCD-up-down counter IC 4510B (IC₃) for producing sequential BCD output.

Outputs from IC₃ is given to input pin of IC₄ (BCD-to-decimal decoder 4028B) in order to decode the output from encoder IC (IC₃). The ten outputs from IC₄ are obtained and each output is connected to base of driver transistor in order to supply gate current to triac.

Here in circuit diagram of multi mode running light we show only one triac firing circuit because of complicated design. But similar triac firing circuit can be connected to each remaining output.

Variable resistor VR₁ and VR₂ is used to control period of interruption and period of running respectively where the direction of running light can be changed by mean of switch SW₂.

3.Twilight Lamp Blinker

    It is very difficult to indicate any obstruction in day time. So to overcome this type of problem the team of dreamlover technology design a cirucit simple and inexpensive twilight lamp blinker,which blinks and can be used near obstructions.

Circuit Description of Twilight Lamp Blinker

The entire circuit of twilight lamp blinker is designed and fabricated around LDR (Light Detector Resistor) and IC CD4093 (IC₁). The preset VR₁ is used to control brightness. For sensor LDR₁ is used that has a high resistance during night (i.e. dark) and a low resistance at day time (i.e. light). The NAND gates (N₃ and N₄) of IC₁ is used as oscillator where high input from NAND gate (N₁) makes the output of NAND gate (N₂) low and vice-versa. The high at NAND gate N₂ result LED₁ blinks by conducting transistor T₁ where transistor T₁ is the LED driver transistor. For more brightness more LEDs is connected parallel to LED₁.

4.Digital Mains Failure/Resumption Alarm

       AC mains fails when over load is connected and this problem is common in now days. Here is the simple circuit using optocoupler Digital Mains failure and resumption alarm, for indicating AC mains fails or resumes by producing alarm sound.

Circuit Description of Digital Mains Failure Alarm

       The circuit digital mains failure alarm is build around optocoupler. The resistor R₁, capacitor C₁ & C₂, with diode D₁ &D₂ provide sufficient voltage to glow internal LED of optocoupler. Here the IC₂ CD4011 is used as oscillator to generate low frequency of 0.662 Hz to 1.855 KHz controlling with preset VR₁. Audio sound is generator by timer IC NE555 (IC₂). The generated frequencies from IC₂ vary from 472 Hz to 1.55 KHz controlling with preset VR₂. For sensing mains fails position of switch SW₁ to point 1 and for sensing mains resumption change the position of switch SW₁ to point 2.