Application scenarios

I believe that students who go to bed or sit down will get a desk lamp or dormitory magic lamp and stick it under the bed for lighting.

As far as I know, 30cm dormitory lamps without dimming are generally priced at less than 10 yuan with free shipping.

If it has a dimmer switch function, it will cost an additional 10 yuan.

So as a student majoring in mechanical and electrical engineering, can I earn the 10 yuan difference on my own?

Let’s learn this circuit below.

working principle

NE55 constitutes a single key switch circuit

An inverting Schmitt trigger is constructed from NE555.

Through R3 and R4 voltage division, the input voltage is set between the two thresholds, so that its output maintains the last triggered state.

C5 is slowly charged through the large resistor R5, and when S1 is pressed, the output state flips and remains.

NE555 constitutes a PWM generator

Charging circuit: D3->RV2 upper half->C8

Discharge circuit: C8->RV2 lower half->D4

Ignoring the diode conduction voltage drop, the time of one cycle is 0.693xRV2xC8.

Component selection

Some people may think that these circuits are a bit extravagant compared to Taobao kits.

But in fact, if the quantity is large, placing orders yourself will not be much more valuable than Taobao.

As a soldering learning board, it is recommended to choose the cheapest electronic components. Can support domestic chips.

Because the component fails, the process of troubleshooting further tests whether you have a thorough grasp of the principles.

# related suggestion

The potentiometers and chips between these circuits are universal. If a certain circuit is damaged, the east wall can be removed to repair the west wall.

Sorted from simple to difficult, teachers are welcome to use them in teaching, but we hope that the URL of this open source page will be added to the courseware to show respect, thank you.

Analog circuit

1. NE555 Ambilight RGB driver
2. LM358 infrared sensor faucet circuit
3. NE555 dormitory magic lamp driver circuit
4. LM358 running water breathing lamp
5. LM358 pickup delay circuit
6. LM358 refrigerator closing reminder circuit
7. LM358 steering gear tester circuit
8. NE555 steering gear tester circuit
9. Dual-way Wien bridge sine wave generating circuit
10. NE5532 infrared reflective switch plus bandpass filtering
11. NE5532 music spectrum light

power circuit

1. Transistor constant voltage and constant current linear power supply
2. MC34063 single inductor buck-boost power supply
3. MC34063 temperature controlled fan
4. MC34063 light control lighting
5. LM358 constant voltage and constant current power supply

Digital circuits

1. CD4017 music doorbell
2. 74LS00 builds JK flip-flop
3. CD4013 three-person answering machine
4. CD4017 running water lamp clock