Simple LED Flip-Flop for Beginners

A very simple Flip-Flop circut for beginners

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Step 1: Parts List

Parts list:
- LED X2
- Resistor: 10K (brown-black-orange) X2

- Resistor: 1K (brown-black-red) X2

- Electrolytic capacitor: 100uF X2

- Transistor: NPN like BC108 X2

- 9V Battery with connector

- Striped wire

- Breadboard

- Spongebob assistant (optional)

Step 2: Resistors

1K : Brown - Black - Red

10K: Brown - Black - Orange

Put resistors on the breadboard like pictures.

Step 3: LED

Put LEDs on the breadboard like pictures.

Notice to polarity of LEDs

Step 4: Capacitors

Put capacotrs on the breadboard like pictures.

Polarity is not very important

Step 5: Transistors

Put transistors on the breadboard like pictures

Step 6: Wiring

Connect point 5 to 11

Connect point 6 to 8

Connect point 2 to 9

Connect point 4 to 12

Connect point 7 to 10

Step 7: Battery

connect + to point 13

connect - to point 10

You can use 3V to 9V battery

Step 8: Run

You can use larger capacitors (like 470uf) for slower flashing and smaller (like 47uf or 10uf) for faster flashing.

Use a larger capacitor (like 470uf) for slower,or a smaller one (like 47uf or 10uf)for a faster blinking.

Step 9: Refrence

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9 Discussions


2 years ago

very well posted .i have made in five miniutes .you have posted step by step .No difficulty faced in making circuit. THANKS .

1 reply

1 year ago

actually, the polarity of electrolytic capacitors is kind of important

2 replies

Question 3 months ago on Step 1

Im trying to make a simple led flip flop forbeginners. 4 questions
1 The first photo shows 4 resistors but the list only mentions 2 or is it one of each type?
2 There is no photo showing the resistors in place before any other component. Are ther any available?
3 Is it 1 of each type of resistor to each capacitor/tansistor/led group?
4 Can further such groups be added with similar connecting wires?
I would be obliged if you could answer these questions

1 answer

Answer 3 months ago

1- Sorry, I had a mistake and forgot it (I will correct it). You need 4 resistors, two 1K for LED and two 10K to connect to capacitor.You can use higher or lower value for resistors. Resistor that connect to LED, control LED brightnes. Ressistor that connect to capasitor control speed of blinking.
2- Images four and five in step 2, and also image on step 7.
3- I dont completly underestand.Each pin of ressitor connect like image or text. I think this schematic help you:

4- for more LED blinking, must use other schematic like this:
for more LED blinking, I offer use IC.
I apologize, my English not good.


4 years ago on Introduction

Thanks for sharing such simple and consise information on Flip-Flops. I love that Sponge Bob was so willing to help you with this!

1 reply