Workshop NE-555 Chip

Workshop NE-555 Chip Sat 20 Nov 2010 14:00 till Sat 20 Nov 2010 19:00 What: Workshop NE-555 Chip Tagline: Yet another Hsb Meetup! Where: HSB Brussels,Belgium Cost: 0 Who: Pastec,linekernel URL:

Who is interested in doing his first steps in this "all you can eat" IC (integrated circuit) NE555 (or cheaper equivalent)?

we ll have a look on theory , we ll learn to do the math , and then let s go for practice , proto , soldering etc...

learn and proto circuit on demand  : ex flashing led , function generator , sound generator , servo-motor control , and much more (like thousand of possible applications )

Date

Saturday 20th november

Flyer

Needs

if you have , bring every electronic you can ex : proto-boards , soldering iron , ... if we know how many people s gonna attend , we ll supply the NE555 (or equivalent) and basics (res ,condos...) we ll also use the java simulator , so if you wana bring your computer ...

Who

• Pastec
• LineKernel
• ptr_
• zoobab
• Jobj
• Arak

Links

• http://praxical.blogspot.com/2009/01/zero-th-order-function-generator.html

Notes

555 workshop http://www.falstad.com/circuit/ pastech docs

http://www.talkingelectronics.com/projects/555/Page1-555.html Schematics : http://en.wikipedia.org/wiki/File:NE555_Bloc_Diagram.svg

• bad for use with batteries / 555 (consumes power in small pulses - so it can perturbate the power line/noise)
• crow-bar ? we'll see later
• oscillator? 555 is making too noisy signals to call it an oscillator probably
• (XR2206 better for oscillating purposes)
• it's a 'timer',it needs 3 external components to make an oscillator (1Hz to 500Hz)
• 28 transistors grouped

1Hz to 500kHz (freq lower then 1 Hz: we call it 'delay' -- but 555 is not really reliable in this

• mark-space : when signal is low (cfr morse-code)
• Rail : distributed power to other components (the farthest, the noisier)

Each pin has a function, if you don't use it, put it down.

pin 2 - prevent the timer from starting until LOW : 'trigger': / is connected to the condensator, detects his power (up or down) pin 4 - stops oscillating : 'reset' pin 5 - ratio: duty-cycle of the oscillation pin 1 - GROUND (not minus!) pin 3 - Output pin 8 - Vcc pin 6 - THRESHOLD pin 7 - DISCHARGE (cfr the condensator/capacity that controls timing)

! check if a 555 is burnt : measure resitance betwin pin 8 and 1 and get 15kohm

pin2: 'trigger' measures the voltage on the capacitor C ( checks if the voltage on the capacitor is lower then 2/3rds of the supply power

ping 6: 'threshold'

pin 7 : 'discharge' whenever 'control flip-flop' triggers it puts pin7 to ground

pin 3: totem-pole : idem as soviet-tank output : can sink 200mA -- drive speaker, small light bulb,... +- 1.7 volt loss sink : drive power - between the pin and ground High state voltage = 13.3 volts (non complete)

slew-rate = rise/ fall-time (here we have 100ns)

the first state of the system is HIGH then the capacitor charges (2/3) , then flop to discharging state

pin 5 - you can apply a voltage to play with the frequency

NPN (negative - positive - negative) (base is in the middle - needs positive voltage to flow current)

PNP (put base on ground to make it conduct)

pin names with a line above: means pin is ACTIVE LOW.