Author Topic: 4: Switches/Bypass/Etc.... (Read 226614 times)

aron · « **on:** October 05, 2003, 07:58:47 PM »

Here is a very simple explanation on how our stomp switches work:

OK, now reference this simple article on bypassing:

http://www.diystompboxes.com/pedals/articles/elbypass.html

aron · « **Reply #1 on:** October 05, 2003, 08:42:16 PM »

Here's how the circuit would be connected to the jacks and LED+resistor:

In the above picture, the left jack is INPUT, the right jack is OUTPUT.
Notice how the LED is connected to the middle lugs. This helps to "isolate" the signals of the input and output but having the middle set of lugs between the two signals.

This is an advantage of using the 3PDT switches. Possible better isolation for signals and ease of use when connectiong an LED to indicate bypassed state.

The LED resistor will vary with your LED type. Start with 1K and lower the value for a brighter LED and raise the value for dimmer glow.

Here is a version with the DC jack:

Andy · « **Reply #2 on:** October 05, 2003, 09:02:23 PM »

I know you have to use ohms law to dtermine the lowest value of the resistor, right? How do you know the voltage drop of the led? I have several that have different numbers on the package. I have several that aren't in packages.

aron · « **Reply #3 on:** October 05, 2003, 09:10:59 PM »

Good Question:

Check out these two links:

http://astro.umsystem.edu/atm/ARCHIVES/MAY00/msg00989.html

and

http://astro.umsystem.edu/atm/ARCHIVES/MAY00/msg00959.html

aron · « **Reply #4 on:** October 07, 2003, 04:05:34 PM »

http://www.muzique.com/schem/led.htm

Cliff · « **Reply #5 on:** October 17, 2003, 07:12:36 AM »

Aron - I finally received my parts from Small Bear, so I'm nearly ready to go. Have to be out of town for the best part of a week, so I'm not quite there. One more question:

I ordered a blue LED from Small Bear, and it arrived with no markings on the package at all. To calculate the size of the resistor, I will need the LED forward voltage and the LED current. The Muzique.com calculator uses default values of 1.8 and 5, respectively, but these give you a value of 1440, pretty far from your approx 470. How do I go about getting the two values for my particular LED. Thanks.

aron · « **Reply #6 on:** October 17, 2003, 02:39:25 PM »

Just do the guessing way. Use a 5K pot in series or clip resistors in series with the LED. Try 2K (two 1K in series) and reduce the resistance until you get the LED the brightness you want.

Once you figure that out, when you order those LEDs again, you can use your found value from then on.

R&D · « **Reply #7 on:** November 06, 2003, 12:44:59 PM »

I believe the 470 ohm is a standard value. I have seen others use a higher resistor to keep current consumption of the 9 volt battery down.

Some of the LED's draw a good amount of current from the 9 volt battery. I usually use a resistance value closer to 1K ohm.

Hope that helps

Joe Bonner · « **Reply #8 on:** November 08, 2003, 12:06:36 AM »

Hi Aron,

Do you mount the LED on perfboard, or do you simply attach extension leads to it and let it hang freely?

Thanks.

Joe

aron · « **Reply #9 on:** November 17, 2003, 01:41:22 AM »

Drill a hole in the box, put an LED plastic mounting ring in there. Push the LED through and run the wires to the switch.

For the millenium, I mounted the perfboard by itself, and ran the wires to the LED and switch.

RDV · « **Reply #10 on:** November 22, 2003, 07:02:15 PM »

I've been using 6.8K for my LED resistors and they're plenty bright for me to see, and the current consumption is around 1 milliamp or less so if you're using a battery it won't drain it too bad.

Regards

RDV

Lanky · « **Reply #11 on:** January 11, 2004, 01:09:13 AM »

Sorry, I'm new to the board and rather inexperienced, but I plan on taking on this project when I get a little more time. One thing I'm sorta confused about though. If I use a 3PDT switch then it eliminates the need of a complicated bypass system such as the millenium, right?

Also, would you reccomend using a LED holder?

Lastly, I paid a visit to the radioshack website and noticed that the stereo input jacks come in packs of two. Is it okay to use two stereo imput jacks rather than one stereo and one mono?

smoguzbenjamin · « **Reply #12 on:** January 11, 2004, 05:22:59 AM »

Welcome to the board!

A 3PDT would eliminate the need for a millenium, yes. And you can use two stereo plugs, sure. LED holders are good

A millenium bypass isn't even that complicated, but it might be a pain to debug if it doesn't work... Using a 3PDT will always work.

Once you get building, you can't stop

Lanky · « **Reply #13 on:** January 11, 2004, 10:49:45 AM »

Thanks for the quick reply.

Sorry one more thing. I also don't need a JFET if I use a 3PDT right?

What would you recomend for a newbie like me? A DPDT with a millenium or a 3PDT without?

smoguzbenjamin · « **Reply #14 on:** January 11, 2004, 02:52:15 PM »

Yes you need a JFET for a millenium, I think. JFETs are voltage controlled devices and regular transistors are current-controlled. So if you use a 3PDT you won't need the millenium bypass.

I'd recommend a 3PDT for anyone, it's a lot simpler but they're not always easy to find, that's why we have aron

Lanky · « **Reply #15 on:** January 11, 2004, 05:08:50 PM »

I reckon I can probably find one somewhere. Theres a few large surplus stores around.

While we're at it, in terms of pronouncing these terms:

Is JFET pronounced 'Jay fet' or 'J-F-E-T'?

and is LED pronounced 'led' or 'L-E-D'?

lol, sorry to trouble you with my newbish questions. :oops:

smoguzbenjamin · « **Reply #16 on:** January 11, 2004, 05:15:55 PM »

It's Jay-fet and led, if you ask me

Don't worry about newbish questions, I was a newbie 4 months ago, just like you are now.

In four months you might be answering questions

It's fun!

Lanky · « **Reply #17 on:** January 11, 2004, 11:13:21 PM »

I don't suppose anyone could take a picture of the inside of thier box, could they?

Also, this shouldn't have any knobs on it unless I adapt the design, right?

smoguzbenjamin · « **Reply #18 on:** January 12, 2004, 01:36:43 AM »

It's got 1 knob, boost

Lanky · « **Reply #19 on:** January 18, 2004, 09:40:06 PM »

I'm having a little trouble figuring out how to attach the pot to the circuit. How exactly is this done?

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Author Topic: 4: Switches/Bypass/Etc.... (Read 226614 times)