GoleLiath's first saber

[GoleLiath]

Ok all, after MUCH studying and practice, I think I have a good first shot at a saber.

I put together what I think is a decent "simple" saber with sound and basic lighting. I used MHS parts for the hilt, and pretty much all TCCS components throughout. I designed it to use a Petit Crouton board, Seoul P4 LED, and two momentary switches for power and effects. I've included a parts list, hilt mockup, and wiring diagram. Scrutiny of all 3 would be greatly appreciated, but I specifically have 4 questions:
1) She's coming in right around 13". I would like to be able to use her one or two handed, am I in a good range for that?
2) Are (2) Li Ion (7.4 V) batteries sufficient for "moderate" use?
3) I did the math for the resistors on the switches, and put them on my parts list. However, it looks like the PC board manages power to them, and they are not necessary, is that true?
4) I would liketo put the switch box on the ribbed section to allow for more space for 1 or 2 handed use (and the potential addition of a sleeve). Is this an ok idea, or will it cause problems? Can the ribbed section be machined?

Thanks again for taking the time to critique!

Component Manufacturer Make Part # Qty
LED Seoul P4 Blue 1
LED Lens Collimator 5 degree Coll5 1
Lens Holder Seoul P4 Holder 1
Thermal Tape TCSS Star Thermal Tape Pad STTAPE 1
Sound Board Petit Crouton Light Meat PC-L 1
Speaker TCSS Premium Pspeaker 1
Speaker Mount TCSS MHS Speaker Mount V2 spkrmountv2 1
On/off switch TCSS SPST Mom Grn Ring Ill Sw SMRNG 1
Effects switch TCSS SPST Mom YLW Ring Ill Sw SMRNY 1
Resistor Yellow TCSS 82 ohm 1/4 w Resistor 82ohm1/4w 1
Battery Pack TCSS 2AA Battery Holder 2AA 1
Rechargbatteries Trustfire Prot 3.7V 900mAh 14500 Li IonTrust14500 1
Recharger TCSS 3.7V - 14.8V Li Ion SmCharg Li-IonCharger 1
Recharge cable TCSS 2.1mm plug adapter 2.1PlugAdapter 1
Recharge Stand TCSS Clear Acrylic Saber Stand Stand1C 1
Recharge port TCSS 2.1mm PowerJack 2.1Jack 1
Quick connector TCSS 2 wire Q conn Qconnector 1
Electronics TCSS 1/8" Adhesive Shrink Tubing 1/8Adhesive 1
Kill key TCSS Kill plug style 3 kplug3 1
Extension TCSS MHS - Ribbed Choke Combo Rccombo 1
Extension TCSS MHS 5" dbl f thread conn DF5 1
Mounting Box TCSS Activation Box Style 11 Box11 1
Mount Box Screws TCSS 4-40 Button Head 440BH 2
Service TCSS Box 11 Mounting Hole Svc Box11Holes 1
Pommel TCSS MHS - MPS Style 3 v2 MPS3v2 1
Sleeve TCSS MHS Sleeve Material (18") MHSSL2-18 1
Blade Holder TCSS MHS LED S: 16 New Sty h/s Sledholder16 1
Service TCSS Blade Holder screw hole svc 1
Blade retent screw TCSS 8/32 x 1/2 8-32vthumb 1
Blade TCSS Show Blade, 1" 40" TCSSShow 1
Safety plug TCSS 1" Hilt Safety Plug TW1PLUG 1

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[Silver Serpent]

1. 13" is a good size for a saber. You shouldn't have any trouble 1 or 2 handed, unless you have really big hands.

2. 2 li-ion batteries are ideal for a PC saber. It was designed to work best with that voltage.

3. The accent led pads on the CF will output 3.3v. You will need resistors for your illuminated switches. Go to http://led.linear1.org/1led.wiz and use 3.3v as your source voltage, and use the other specs from your illuminated switches to calculate your resistors.

4. Yes, you can put the switch box on the ribbed section. The really long latching AV switches may not fit in there, but most other switches will. The switch box can help them fit better.

You'll need to add wiring (and resistors) from the LEDs on your illuminated switches to the accent LED pads on the PC. The switches will not illuminate automatically. Check the PC manual for some good diagrams.

[Zzan]

Are there SPST momentary AV switches in stock? If so I would swap out the DPDT ones with the SPST ones. The DPDT ones may be too long to put in a ribbed section. They don't have much clearance on a normal section even with a mounting box, so it is unlikely they will fit in a ribbed section even with the mounting box. It doesn't look like from your wiring that you are wiring the second side of the switch so get the single pole/single throw ones instead.

[GoleLiath]

Hey, thanks for all of the really great advice! I learned a couple of things:
- Wiring up the switches to the PC doesn't give power to the LEDs, that needs to be done separately
- The resistors for the switches is needed b/c the LED power is wired separately, and not controlled by the board

I made changes to the design and wiring accordingly.
- I changed out the DPST switches for the shorter SPST ones (same colors, I'm not concerned w/stock yet, this is still "build it right" for me).
- I added power for the LED on the switches
- I recalculated the resisters from 7.4V VS from the battery to 3.3 VS from the board. It looks like the green switch (running at 3.3) doesn't need a resistor, but the yellow (at 2.1) does? I calculated that out to 60, and defaulted to the next highest (82). Did I do this math right?

Updated the wiring diagram, and parts list and could use more scrutiny on both...

[Silver Serpent]

You'll want to put a small (1 ohm or so) resistor on the green switch for good measure. You can get heat buildup if you don't use one. Trust me, I know from experience :)

There are 68 ohm resistors that would work on the yellow, though I don't see them in the store. The 82 ohm will work, and your eyes probably won't notice the difference in brightness.

[GoleLiath]

Cool, thanks Silver.

Does everything else look ok? How about the new wiring diagram, did I get everything set up right?
Also, I'm a little confused by the resistors. Why would I use a 1ohm 5w resistor, vs a 1 ohm 2 w. I guess I'm basically saying that I understand where the ohm's number comes from, but what does the wattage? I can't figure it out, even after reading the Ohm's law postings...

[KuroChou]

the wattage is the maximum amount of power the resistor can handle, before burning up. If you're using a 3W+ LED, then you should really be using a 5W resistor.

[GoleLiath]

Ok, thanks. But if the LED's are 3.3V and 2.1V at 20 mA, doesn't that mean their wattage is .066 and .042 (W=A*V) respectively? Wouldn't that mean that a 1/4 W resistor would be sufficient, or am I calculating something wrong?

[KuroChou]

for your accent/switches, yes 1/4W will be fine. I Incorrectly assumed you were talking about your main LED.

[GoleLiath]

Ah, ok, understood, thanks. So, for my purposes then, there's zero difference between the 1ohm 2w and the 1ohm 5w? Either would do the job, but the 5w is even more overkill than the 2w?

[Zzan]

Remember space is at a premium inside your hilt. It's hard to realize without the parts physically in front of you. You will want to get a 1/4watt or 1/2 watt resistor for your accent LED's. They can be easily and cheaply found locally for most people. I bought an assortment pack of 500 1/4 watt resistors from a well known electronics store locally for under $10.00.

Resistors that can handle more power are bigger, and will take up more room, so while it is ok to use one that can handle more power, it isn't always the best choice. A 1/4 watt resistor isn't much larger diameter than the wire you are using to wire and can be heatshrunk right in line and not take up any more room than the wire would by itself.

[GoleLiath]

Ok, that's a good point. It's hard for me to tell scale, from just the pics on the TCSS store.
Anyone else have an comments on the wiring diagram, before I try to get my order in??
5965

[Silver Serpent]

The 5 watt is going to be physically larger than the 2 watt. If space is an issue (and it usually is) you'll want the 2 watt. Your electrical circuit won't care either way, they'll both work fine.

edit: Zzan beat me to the punch.

[Skottsaber]

To do with LEDs and resistors off of PC/CF boards.
The pads are at 3.3v, but the microcontroller can only handle up to ~20mA (safe side) being drawn from those pins. Therefore you Always Use a Resistor™ or you won't have your PC working for long.
So calculate your LEDs to run at 20mA or less.

[GoleLiath]

Haven't forgotten about this build, I'm actually chomping at the bit to get started!

Just waiting for the store to restock on a few key parts... :(