Good sound FM transmitter

Good FM transmitter

Hi friends and electronics lovers,  Here is a simple good sounding FM transmitter circuit ( cct). The inductor is gauge 22 or 24 wound on 3mm inches mail about 7turns
NOTE:
you can replace the 2N2222 with Bc547 or c1815. The integrated circuit ( IC) is an audio amplifier which help the generator in of the tx to generate a good frequency modulation output.

How to test after building it
1. Put your radio ON
2. Put your transmitter ON
3.Bring them closer and tune your radio receiver to search station. (91.0- 71-5)

4. If you are having any interference or did not received the transmitter Chanel  you now adjust the fix inductor a little bit, as you are adjusting the inductor the frequency is move from 91.0 /71-5 to another freq.

CIRCUIT DIAGRAM :

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How to drive 7segment using CD4026 and push to on switch

How to drive 7segment using CD4026 and push to on switch 

Today we are going to learn how to drive seven segment (7seg) display  manual and automatic. 

A 7segment is a light emitting diode (LED) segment in common anode (CA) or common cathode (CC)   

NE555 was used to drive it on automatic mode,  while push to on was used to drive it in manual. 

It was connected in voltage divider as a pull up resistor.
If you are using the manual that means you will not use the auto.

The manual allows you to press it through the PUSH TO ON switch to count from zero (0) to nine (9). While the AUTO count on its own depending on the speed timing, you can adjust or reduce the speed by putting a variable resistor on  R2 which is 100k (code104)

MANU:

   

 AUTO:

CIRCUIT DIAGRAM :

Is a simple circuit that can count from 0 to 9, but you can still modify it to reach up to thousands by adding more CD4026 which is the main 7segment driver counter, by connecting pin 5 which I labeled as(Q2) Is the CARRY OUT (CO)  to another 4026, at pin 1 which I also labeled( Q1) in the cct diagram is the clock input and follow by the configuration.


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Automatic emergency light

Automatic emergency light  

Hello friends today we are going to build a simple auto emergency light using some few components. 

Component needed are as follows:

RESISTORS

  1k  2pcs

  2.2k  2pcs

  10k 3pcs

  10R (ohms) 2pcs

  4.7k   1

  LDR   1

CAPACITORS

1000mf   1

100mf     2pcs

TRANSISTORS

BC547  2PCS

INTEGRATED CIRCUIT (IC) 

NE555 OR LM555

TRANSFORMER

Step down 220/12volt 1

DIODE 

1N4007

LED

white 9pcs, with 1 red 

BOARD 

vero board or good pcb

SWITCH
Normal close 1

BATTERY 

See text

CIRCUIT DIAGRAM:

In the cct diagram above you can replace R5 with 10k potential meter 10k pot(code 103),  to enable you to adjust the light dependence resistance (LDR) in such a away that it can be able to sensed the day and the night to activate the light emitting diodes (LED) 

How it works 

The hart of the circuit is the NE555 , pin 8 is the VCC (+) while pin 1 is the GND (-) The LDR and R5 where connected in voltage divider send to pin 2,pin 6 from the point of connection. pin 2 and pin 6 were

connected to monitor when their is ⅔ volt across the point of LDR and R5, pin 3 is the output which send a high/low signal to the Bc547 to turn the light ON or OFF,  Pin4 is the reset which off the entire sectary when the  pin is connected on GND ( -)

When there is a public mains it sense it through the R1, which activate the Q4, Q4 will now send a negative signal to pin 4 which is the reset  pin of the IC the light will now shut down automatically,  it happens vice versa

The battery is a rechargeable battery that may be 3.7volt or 7.3volt with a good capacity
Example a portable DVD player battery 7.3volt / 2000mA

It had a good volt and current, but you can also double both in parallel or in series in *parallel current increase
*series voltage increase.


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