555 timers are one of the most popular and versatile ICs on the market. In the previous lesson, we learned how 555 timers get used in circuits. There are three main types of circuits in which they are used, monostable, bistable, and astable. Astable circuits are likely the most common use for 555 timers. In this episode, Karen shows how to create an astable circuit using a 555 timer. Follow along as she uses resistors and capacitors to create an RC circuit to affect the timing of the circuit. Karen’s final circuit uses a 4-position DIP switch to allow for the use of 4 different resistors and therefore 4 speeds to control the flashing of LEDs. While Karen uses this circuit to create flashing lights on a headband and a hat, the uses are endless. Try your hand at making the circuit and use it to make art, on decorations, or create warning lights. Come up with other ideas for how to use this circuit and post them in the comments below!
| Final Schematic | Circuit Layout |
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Supplemental Content:
- The Learning Circuit: 62: How 555 Timers Work
- The Learning Circuit: 63: LED Dominos Using a 555 Timer
- The Learning Circuit 66: 555 Timer Modes Explained
- 555 Timer Voltage Inverter by fmilburn
- 555cc by jc2048
Bill of Material:
| Product Name | Manufacturer | Quantity | Buy KitBuy Kit |
|---|---|---|---|
| Electrolytic Capacitor, Miniature, 10 µF, 25 V, 515D Series, ± 20%, Radial Leaded, 5 mm | Vishay | 1 | Buy NowBuy Now |
| Ceramic Disc Capacitor, 0.01 µF, 100 V, ± 20%, 5 mm | Vishay | 1 | Buy NowBuy Now |
| LM555CN - Timer, Oscillator & Pulse Generator IC, TTL Compatible, Astable, Monostable, 4.5 V to 16 V, DIP-8 | On Semiconductor | 1 | Buy NowBuy Now |
| Through Hole Resistor, 220 ohm, 400 mW, ± 1% | Vishay | 1 | Buy NowBuy Now |
| Through Hole Resistor, 1 kohm, 500 mW, ± 1% | TT ELECTRONICS / WELWYN | 1 | Buy NowBuy Now |
| Through Hole Resistor, 22 kohm, 250 mW, ± 1%, Axial Leaded, 200 V | TE Connectivity | 1 | Buy NowBuy Now |
| Through Hole Resistor, 47 kohm, 250 mW, - 1%, 200 V, Axial Leaded | TE Connectivity | 1 | Buy NowBuy Now |
| Through Hole Resistor, 100 kohm, 250 mW, ± 1%, Axial Leaded, 200 V | TE Connectivity | 1 | Buy NowBuy Now |
| Through Hole Resistor, 220 kohm, 250 mW, ± 1%, Axial Leaded, 250 V | Multicomp | 1 | Buy NowBuy Now |
| Prototype Board, 25 x 15 grid, 1.6 mm, 72 mm, 47 mm | Multicomp | 1 | Buy NowBuy Now |
| LED, Cool White, Through Hole, T-1 3/4 (5mm), 20 mA, 3.2 V | Cree | Buy NowBuy Now | |
| Slide Switch, SPDT, On-On, 2.54mm, Through Hole, Side, 4 A, 250 V | APEM | 1 | Buy NowBuy Now |
| DIP / SIP Switch, Raised Rocker, 4 Circuits, Rocker, Through Hole, SPST, 30 VDC, 150 mA | GRAYHILL | 1 | Buy NowBuy Now |
| 2226TG -Contact, 2226 Series, Socket, Crimp, 24 AWG, Pin | Multicomp | 2 | Buy NowBuy Now |
| 2226A-02 -Connector Housing, 2226 Series, Receptacle(Female), 2 Positions, 2.54 mm | Multicomp | 1 | Buy NowBuy Now |
| Wire-To-Board Connector, 2.54 mm, 2 Contacts, Header, Male, 90deg | AMP - TE CONNECTIVITY | 1 | Buy NowBuy Now |
| 9V battery snap, flexible | Multicomp | 1 | Buy NowBuy Now |
| Battery, 9 V, PP3, Alkaline, 565 mAh | Pro Elec | 1 | Buy NowBuy Now |
| Hook-up Wire Spool Set - 22AWG Solid Core - 10 x 25ft | Adafruit | 1 | Buy NowBuy Now |
Additional Parts:
| Product Name |
|---|
|
LED strand or chosen Light source |
Top Comments
Looks like you're selling this wrong; you have four bits for speed setting. Therefore you have 16 Speed settings when you have resistors switched to be parallel, forming another value.
I like how it…
An option might be to swap the DIP switch for a variable resistor. Depends if the application benefits…