Ordering

I recently placed an order for DIP CD4017s from Futurlec, to build a prototype with on a breadboard. I want to build a prototype so that I can tweak the timing based on the resistors and capacitors; in that effort, I've ordered a few trimpots to help make quick and fine adjustments. I've heard their shipping speeds are very slow (at $4USD postage, I'm not looking to complain). Check out their value packs: 300 5% 1/4W sorted resistors for $2.95USD, 50 Assorted linear IC's for $5.95USD to name a few standouts!

Dear Thomas,
Many thanks for your order as shown below,

Qty ItemNumber Unit Price Total Price
----------------------------------------------------------
1 RES14WPACK 1/4W Resistor Value Pack 2.95 2.95
1 ELEPACK Electrolytic Capacitor Value Pack 3.95 3.95
3 CD4017 CD4017 Decade Counter/Divider 0.30 0.9
3 LMC555CN LM555CN - CMOS 555 Timer 0.45 1.35
3 BUZZERMODULE Active Buzzer Module 0.90 2.7
1 R010M14W 10Mohm 1/4W 5% Carbon Film Resistor 0.10 0.1
1 R0047M14W 4.7Mohm 1/4W 5% Carbon Film Resistor 0.10 0.1
1 R0033M14W 3.3Mohm 1/4W 5% Carbon Film Resistor 0.10 0.1
1 R010K14W 10kohm 1/4W 5% Carbon Film Resistor 0.10 0.1
3 C001U50E 1uF 50V Radial Electrolytic Capacitor 0.05 0.15
1 CERPACK Ceramic Capacitor Value Pack 2.95 2.95
2 TRIM2M 2M 1/2W Min. Horizontal Pot 0.15 0.3
2 TRIM50K 50K 1/2W Min. Horizontal Pot 0.15 0.3
1 TRAPACK Transistor Value Pack 4.95 4.95
1 DIOPACK Diode Value Pack 2.95 2.95
----------------------------------------------------------
Sub-Total 23.85
Postage 4.00
Total 27.85

Analysis

While I'm waiting on the shipment, I've been using LTspice to simulate the circuit and get a better understanding of the behavior. I'll post my explanation and analysis in the next update. Over all, LTspice has been difficult to learn but fascinating to see how the components behavior under varying circumstances. I don't own an oscilloscope, so there is no other way for me to see these interactions in such detail. I'll be using the LTspice simulation to explain the circuit in the next update.

Above, you can see the voltage potential at every other LED anode connected to the CD4017. This produces a cascading effect in sequence with the slowing clock pulses from the 555. In this simulation ten LEDs are used (one for each output of the 4017), but only six will be used in the final design.

This is my first analog circuit, so it's been fascinating to see behaviors and characteristics jump off of the datasheet and onto the (virtual) bench!

Here's the netlist for those who want to follow along. Note: you'll need to add the library and symbols from CD4000.zip linked on the project page and update the .lib directives to point to the correct libraries.

* /Documents/LTspice/555_roulette.asc
XU1 0 N003 N006 VCC NC_01 N003 N003 VCC NE555
V1 VCC 0 3.7
R1 0 N003 4.7Meg
C1 N003 0 100n IC=0
R2 N003 N005 10K
Q1 N005 N002 VCC 0 BC557B
R3 N002 VCC 3.3Meg
R4 N001 N002 10Meg
S1 0 N001 N004 0 SW
V2 N004 0 PULSE(0 1 0.1 0 0 0.1 0 1)
C2 VCC N001 1µ
XU2 0 0 N006 N007 N009 N010 N011 N012 N013 N014 N015 N016 N017 0 VDD 0 CD4017B VDD=3.7 SPEED=1.0 TRIPDT=5e-9
D1 N007 N008 QTLP690C
D2 N009 N008 QTLP690C
D3 N010 N008 QTLP690C
D4 N011 N008 QTLP690C
D5 N012 N008 QTLP690C
D6 N013 N008 QTLP690C
D7 N014 N008 QTLP690C
D8 N015 N008 QTLP690C
D9 N016 N008 QTLP690C
D10 N017 N008 QTLP690C
R5 0 N008 4.7Meg
.model D D
.lib /Library/Application Support/LTspice/lib/cmp/standard.dio
.model NPN NPN
.model PNP PNP
.lib /Library/Application Support/LTspice/lib/cmp/standard.bjt
.tran 0 15 0
.model SW SW(Ron=1 Roff=1000G Vt=0.1 Vh=0)
.include CD4000.lib
.lib NE555.sub
.backanno
.end

 I'm hoping that the simulation gives me enough confidence to build the PCB. I plan on using 0805 SMD resistors and capacitors, so regardless of the values, the PCB layout should remain the same. If I can get the PCB ordered sooner rather than later, that should help eliminate multiple wait times.