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Baby's First Hardware Prototype




  Some tips before you start to build your Prototype: 
(1) Double check (triple check) the schematic against the DATA SHEETs!

 (2) Using a pen, draw a pictorial drawing of the circuit from the schematic, that is, draw the dip on its back-- numbering the pins clockwise-- use a socket having a greater pin count than the IC dip, using the extra positions for related circuit components, i.e., resistors and caps.

 (3) With a pencil--Draw the connections between the pins.

(5) Component Placement using IC Sockets TOP
  (4) Don't Forget the BYPASS CAPS!!!
More on Bypassing... 
Always SOLDER in Bypass capacitors! 
(6) --NEVER NEVER NEVER!---->
NEVER EVER use the white nylon Solderless Breadboard (The same plug-boards you've used in your previous "Labs.")
 
 

..
 



Your Unwrap Tool is to Wire Warping as an Eraser is to Writing.
30 Ga. Wire Wrap Gun
30 Ga. Unwrap Tool
30 Ga. Wire Wrap Wire Stripper
Using the Wire Stripper on 30 Ga. WW Wire

3.. Then pull the wire length-wise, while at the same time squeezing the Stripper's Teeth even harder --cutting the end of the Wire.
Several Simultaneous Operations:
1.. Grab the end of the WW wire in the
Stripper's Teeth.

2.. While holding the end in the teeth, pull Down on the
Wire, into the Stripping Groove, until the Kynar
Insulation Breaks.

4.. The resulting ~ 3/4 inch bare "Shiner" will be nick free, and ready for wrapping.

Note: The short section of Insulation just before the bare wire (shiner).  This is a Modified Wrap: For protection against nicked or broken wire, the first 3/4 turn--wrapped on the WW Pin --is Insulation. See Below 
Keeping the wire Nick Free is of the utmost importance! Otherwise the wire can appear to be wrapped, but in fact be broken--making either no or intermittent contact. Finding such a failure can be a Bitch!!
Example of Wire Wrap on IC Socket Post,
again, using a Modified Wrap.
Wire Wrap Bit & Sleeve
Note: The short section of Insulation just before the bare wire (shiner).
.
CAUTION: 
The wire wrap Bit & Sleeve are very fragile! 
Try not to DROP the Gun; it usually hits on the bit and sleeve first (where else); which will bend it, leaving you with a inoperable gun. It is very very difficult to straighten it back to its original condition!

Some guns come with a lanyard meant to use for hanging around your neck. Though it takes a little getting use to, it will save you keester!
 

.
5.. In troubleshooting:
Don't be shy about trying several NEW parts--you could have a bad part!
This includes resistors and caps.

Also, remember more than 80% of all problems could have been found using your EYES! 

"--gee, I didn't see that the power cord was out of the wall..."
6.. Please Always Check the DATA SHEET.
You may be using a resistor for Ra or Rb that is too low in value, e.g., the 555 doesn't like Ra values below ~5K.

7.. Pin 5--the Voltage Control pin of a 555 timer must be A.C. coupled! If you Direct Couple pin-5, you force a bias on it that could prevent it from ever charging the timing cap to 2/3 Vcc
thus rettriggering!

8.. DO NOT use electrolytics for the timing caps.
 

When prototyping your first circuit:
1) The circuit should be put on a printed circuit board (PCB)
2) having lots of ground plane;
3) plated thru holes;
4) the interconnection should be "Wire Wrap" using
5) 30 Ga., kynar insulated, WW Wire.
6) The Sockets should be of the Machined-Pin, Wire Wrap types;
7) All Components (except bypass capacitors & Voltage Regulator components--components that will never change their required value) should be "plugged" into the same type of sockets and their position should be as close to the other components they are connected to: Wire Wrap Machined sockets
8) Once completed, the WW socket Pins can & should be cut short--reducing stray parasitic inductance and capacitance.
9) Power Supplies: should be, either "Hard Wired" to the circuit of interest, or plugable using the following precautions:
  a.. If there is more than one voltage involved, e.g., +/- 12-V: install ~ >1 amp reversed diodes across the input of each power input. This will prevent "Circuit Injury" due to reverse voltages. This has to do with "Hot Plugging."
..

DOs

DON'Ts

1) The circuit should be put on a printed circuit board (PCB).

2) The PCB Should have lots of ground plane.

3) The PCB Should have plated thru holes.

4) Use Wire Wrap interconnections.

5) Only 30 Ga., kynar insulated, WW Wire.

6) The Sockets should be of the Machined-Pin, Wire Wrap types.

7) All Components (except bypass capacitors & Voltage Regulator components--components that will never change their required value) should be "plugged" into the same type of sockets and their position should be as close to the other components they are connected to.

8) Once completed, Shorten (cut) the WW Pins.

9) Power Supplies: either "Hard Wired" to the circuit of interest, Or pluggable using protection.

10) When dealing with multiple wires as in a bus, always separate them --Never "Bundle."

11) Always make sure the power is OFF when you plug & unplug your circuit from the power supply. Always Disconnect the power supply from the Mains (120 VAC).

12) Always make permanent connections between your circuits and the power supply.

13) Always Power Down--and wait n seconds--before plugging in ANY component.

14) When HANDELING your circuit/circuit board, Always, FIRST make electrical contact with the circuit board's COMMON and your fingers, before plugging in any Component.
 

1) NEVER EVER use the white nylon plug-boards that you have used in your previous "Labs."
2) Never Solder wires (except for Bypass capacitors & power supplies).: Use Wire Wrap.

3) Never use bare "Perf-Boards" that have no copper layer(s) or plated thru holes.

4) Never use "Hand" wire Wrap tools--always use WW Guns!

5) Never use any Socket that isn't Machined-Pin.

6) Never use etched or milled PCBs for your very First prototype board.

8) Never use excessive wire length.

9) Never leave WW sockets with unnecessary pin length.

10) Never run many wires (e.g, digital bus) close togather--Never "Bundle" them.

11) Never plug & unplug your circuit from the power supply while it is ON.

12) Never make "Temporary (e.g., alligator clips) connections to the power supply: Always make them permanent.

13) Never plug in any device to a circuit while it is powered!

14) Never plug in a Semiconductor device without FIRST making electrical contact with the circuit board's COMMON and your body.
 

A Word about SOLDERING

1)_ The soldering iron tip should be tinned and clean 

2)_ Use a wet sponge to clean the tip 

3)_ Heat the pieces to be soldered together hot enough to melt the solder. Of course melting solder on to those pieces will help to speed up this heating process. --see next step

4)_ In one simultaneous motion: as you apply the solder to the "joint" use the iron to help melt the solder and release the rosin flux (in the solder core) to allow 'wetting'  action of the molten solder to FLOW into the joint; it should 'wick' into the joint. 

5)_ If you have done it correctly, the soldered joint will SHINE and appear as if it has flowed; as opposed to beading up. The surface tension of the melted solder is what we are talking about--just like water. Until the beading breaks and flows, the soldering operation is not complete.
 



 White Nylon Proto-boards ARE EVIL

The white nylon proto-boards are constructed for ease and speed of use; however, they don't allow for adequate bypassing of individual devices--there is too much stray inductance, negating most of the bypass capacitor's usefulness.

Remember, a 555 has transistors in it capable of generating rise and fall times in the nanoseconds (ft ~ 200 MHz). Also the proto-board uses connectors (wire receiving sockets) that are daisy-chained and close together: all adding parasitics--inductive and capacitive--generating crosstalk (unwanted feedback, etc.) and causing circuit instability.

The resulting circuit design that one "made to work" on the proto-board, can end up not working when committed to the final PCB--the parasitics are gone. Likewise, a good design will not work as intended, no matter what you do to the circuit.

If the rules (data sheet) aren't followed you can have some pretty weird things happening; and excuses like, "the dog ate my homework," or "the Devil made me do it," just don't fly anymore.
 


A New Discovery!  __For Me 
"Son of a Bitch," where have you been all my Life?

Something called  Schmartboard
For Prototyping Surface Mount Devices!
See their Videos: http://www.schmartboard.com/index.asp?page=resources_howto
Check out their forum: http://forum.schmartboard.com 

They give away free products Everyday on www.facebook.com/schmartboard
Tweet: www.twitter.com/schmartboard

This is not an AD, it's a tip...


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