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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
Switches and Standards
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bugbrand



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PostPosted: Wed Feb 13, 2008 5:18 am    Post subject: Switches and Standards Reply with quote  Mark this post and the followings unread

I'm trying to plan some rules before busting out some ideas...
I'm currently mulling over whether to have some internal buss routings, but'll probably leave this for now -- it could be useful for quicker routing, or maybe people could implement it easily with normalised jacks (unless you're sensibly going for bananas for the true science lab experience!!!)

Anyways, some initial rule ideas:

1) On/Off switches on inputs - just simple SPDT switches to allow quick'n'easy switch On/Off of control / data / clocking inputs. I think Mosc has talked about similar with regards to CV inputs (maybe on Buchla systems?). I see this as a really useful feature for hands-on playability

2) As discussed in other threads, all inputs would generally be tied to ground with a 100k resistor

3) I'm also reckoning that all inputs should go through a diode on their way in and think this is especially necessary on banana systems -> it means signals can only go IN and not out - I've found that when connecting things together in my current clocking setups its quite possible to get things to affect each other when not really desired!
(note that I'm expecting any input signal to have been created within the Lunetta system so there's no need for over-voltage protection etc)

(what do people think on this? -- you can also add more diodes for more inputs -- that works, basically, as an OR input)

4) We need to talk more about switches, I think! I've still got quite a few On/On/On toggles -- some simple/passive three way switches will be very useful and I oughta make some rotary versions too. I think for good use you'll want quite a few of these sort of things -- its the sort of thing that should be put into a module if you've got a little panel space left over!


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Standard Input configuration?
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widdly



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PostPosted: Wed Feb 13, 2008 5:30 am    Post subject: Reply with quote  Mark this post and the followings unread

You could use an LED instead of the diode.
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bugbrand



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PostPosted: Wed Feb 13, 2008 6:36 am    Post subject: Reply with quote  Mark this post and the followings unread

widdly wrote:
You could use an LED instead of the diode.


Hmm, maybe, yes!

But, that makes me think of another standard (for those who like flashing lights all over the place) -- LED indicator on all OUTPUTS. I think having them on inputs would be overkill...

On that front, I'd presume that CMOS gates would probably be happy just to have an LED hung straight off their outputs with, say, a 2k2 resistor in series -- guess if you're going for a chip with lots of outputs it'd be best to check how much total current the chip can source though!

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widdly



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PostPosted: Wed Feb 13, 2008 6:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Loads of flashing LED's are a must.

Maybe if there are LED's hanging off every output then you wouldn't need them on the inputs.
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Clack



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PostPosted: Thu Feb 14, 2008 2:30 am    Post subject: Reply with quote  Mark this post and the followings unread

bugbrand wrote:

On that front, I'd presume that CMOS gates would probably be happy just to have an LED hung straight off their outputs with, say, a 2k2 resistor in series -- guess if you're going for a chip with lots of outputs it'd be best to check how much total current the chip can source though!


you mean just put the LED in series to the output? Will LED's cause a lot problems or is it easy with logic?

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widdly



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PostPosted: Thu Feb 14, 2008 3:08 am    Post subject: Reply with quote  Mark this post and the followings unread

It's recommended not to drive more than 10mA off a 4000 series output.

I guess you could drive a transistor of the logic outputs like they did here. http://ourworld.compuserve.com/homepages/Bill_Bowden/4017-2.gif

Another solution would to feed the outputs to a 4050 Hex buffer and drive the leds off the 4050 outputs. You could also use a 4049 inverter and have the led wired as a sink not a source.
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Uncle Krunkus
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PostPosted: Thu Feb 14, 2008 6:10 am    Post subject: Re: Switches and Standards Reply with quote  Mark this post and the followings unread

bugbrand wrote:
I'm trying to plan some rules before busting out some ideas...
I'm currently mulling over whether to have some internal buss routings, but'll probably leave this for now -- it could be useful for quicker routing, or maybe people could implement it easily with normalised jacks (unless you're sensibly going for bananas for the true science lab experience!!!)

Bananas (or maybe mini bananas) should be the standard, it would help to stop cross-patching as well.
Quote:

Anyways, some initial rule ideas:

1) On/Off switches on inputs - just simple SPDT switches to allow quick'n'easy switch On/Off of control / data / clocking inputs. I think Mosc has talked about similar with regards to CV inputs (maybe on Buchla systems?). I see this as a really useful feature for hands-on playability

SPDT with momentary on one side, off in the middle, would give you an on/off/forced high option. Good for testing/playing.
Quote:


2) As discussed in other threads, all inputs would generally be tied to ground with a 100k resistor

3) I'm also reckoning that all inputs should go through a diode on their way in and think this is especially necessary on banana systems -> it means signals can only go IN and not out - I've found that when connecting things together in my current clocking setups its quite possible to get things to affect each other when not really desired!
(note that I'm expecting any input signal to have been created within the Lunetta system so there's no need for over-voltage protection etc)
The standards should also include a module for coming in from the outside world (which does have over voltage protection) and out to other equipment (similar precautions?)
Quote:


(what do people think on this? -- you can also add more diodes for more inputs -- that works, basically, as an OR input)

4) We need to talk more about switches, I think! I've still got quite a few On/On/On toggles -- some simple/passive three way switches will be very useful and I oughta make some rotary versions too. I think for good use you'll want quite a few of these sort of things -- its the sort of thing that should be put into a module if you've got a little panel space left over!


And the transistor buffered (no worries about fanout) LED on every output is a must!
"Burn baby burn! Disco inferno! Burn baby burn!" Laughing

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mosc
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PostPosted: Fri Feb 15, 2008 8:49 am    Post subject: Reply with quote  Mark this post and the followings unread

It is best to make all of the inputs ACTIVE LOW. So you can add a pretty hi resistance to pull up each input. 500K or 1M is probably all you need since the CMOS inputs are very HI Z.

I don't really think it's necessary to have a diode on each input. (Just experience here).

The neat think about having ACTIVE LOW inputs is that you can then just plug in a patch cord and touch it to the grounded front panel to "play" it.

It's not a great idea to paint the front panels on a Lunetta. The best thing is a grounded aluminum panel.



For the LEDs - a fancy system would use buffers, but if you can get some low current LEDs, just hang them directly on the outputs though current limiting resistors.

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jnuaury



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PostPosted: Sat Mar 01, 2008 3:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

would you mind elaborating a little bit on "active low" inputs?
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mosc
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PostPosted: Sun Mar 02, 2008 11:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, it's about what you call a 1 and a 0.

If the input is edge triggered, make it so that a negative edge will trigger.

If it is a logic input, make it such that grounding the input will activate it.

Switches just go to ground.

This isn't a hard and fast rule, but it's very convenient to plug in a banana cable and ground the other in on the front panel to get your circuits to work. If the inputs require Vcc the logical 1, then it is a little more problematic. Sometimes putting an inverter on the input is all that is needed.

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