[PD] electro-mechanical piano (player piano) - Arduino, Solenoid Issue

[Ed Kelly]

Oh, thanks.

That was dumb I didn't remember that!

Is it really 2 volts drop for an LED? I should know this stuff...
Ed
 
Ninja Jamm - a revolutionary new music remix app from Ninja Tune and Seeper, for iPhone and iPad
http://www.ninjajamm.com/


Gemnotes-0.2: Live music notation for Pure Data, now with dynamics!
http://sharktracks.co.uk/ 


>________________________________
> From: Mikael Fernström <mikael.fernstrom at ul.ie>
>To: Ed Kelly <morph_2016 at yahoo.co.uk> 
>Cc: Charles Z Henry <czhenry at gmail.com>; Epic Jefferson <jeffreyconcepcion at gmail.com>; pd-list <pd-list at iem.at> 
>Sent: Thursday, 8 August 2013, 0:26
>Subject: Re: [PD] electro-mechanical piano (player piano) - Arduino, Solenoid Issue
> 
>
>
>note that you have to subtract the voltage drop over the LED, hence it's R = (Vsupply - Vled)/ Iled, e.g. (5-2)/0.02 = 150 Ohm
>
>
>/Mikael
>
>
>
>
>On 8 Aug 2013, at 00:19, Ed Kelly <morph_2016 at yahoo.co.uk> wrote:
>
>Check Ohm's law.
>>
>>
>>V=IR, so the resistor you choose is the voltage you provide to the LED divided by the current it draws.
>>
>>
>>e.g. if the LED draws 20mA and you power it from 5V, then the resistor you need is 5/0.02 = 250 ohms in series with the LED. This current is drawn from the positive voltage supply through the resistor and then the LED, and then the transistor.
>>
>>
>>This is a fairly good tutorial:
>>http://www.ehobbycorner.com/pages/tut_transistors.html
>>
>> 
>>Ninja Jamm - a revolutionary new music remix app from Ninja Tune and Seeper, for iPhone and iPad
>>http://www.ninjajamm.com/
>>
>>
>>
>>Gemnotes-0.2: Live music notation for Pure Data, now with dynamics!
>>http://sharktracks.co.uk/ 
>>
>>
>>>________________________________
>>> From: Charles Z Henry <czhenry at gmail.com>
>>>To: Epic Jefferson <jeffreyconcepcion at gmail.com> 
>>>Cc: pd-list <pd-list at iem.at> 
>>>Sent: Wednesday, 7 August 2013, 20:41
>>>Subject: Re: [PD] electro-mechanical piano (player piano) - Arduino,	Solenoid Issue
>>> 
>>>
>>>
>>>On Wed, Aug 7, 2013 at 12:05 AM, Epic Jefferson <jeffreyconcepcion at gmail.com> wrote:
>>>
>>>Hey Charles,
>>>>
>>>>
>>>>it seems like this might work. i got some pnp transistors and built the circuit from julianvogels site.
>>>>The only problem is that the LED on the test circuit barely lit up. I think it's because the transistors are not for 20mA, none were available. i'll check another electronics store to see if i find some.
>>>>
>>>
>>>
>>>I think you just need smaller resistors.  Every transistor in a 3-pin package I've ever seen could run 20mA or much greater.  Swapping the transistors will have no effect on the amount of current.
>>>
>>>
>>>Chuck
>>>
>>>
>>> 
>>>
>>>>>There are two ways to solve your problem:
>>>>>
>>>>>The proper one is to use PNP transistors or P-channel mosfets (remember
>>>>>I already told you about that ? :))
>>>>>
>>>>>See this document, you can find the wiring at the end:
>>>>>http://julianvogels.de/wp-content/uploads/2013/06/stromkreis_transistorschaltung_final-1024x627.png
>>>>>
>>>>>http://julianvogels.de/extending-pwm-output-pins-with-a-texas-instruments-tlc5940-led-driver/
>>>>>
>>>>>
>>>>>The good enough one is to put a pull-up resistor (10k works) on every
>>>>>NPN transistor base, and use the TLC as a pull down. In this case, the
>>>>>on-time on the TLC corresponds to the off-time on the solenoid. Also
>>>>>when the arduino reboots and every time the BLANK is issued, every
>>>>>solenoid will act for a veeeeery short time. This can be a big problem
>>>>>in your project. I did this for a 96 channels motor+led strip system,
>>>>>and I regret not using PNPs instead.
>>>>>
>>>>>
>>>>>Enjoy,
>>>>>
>>>>>--
>>>>>Charles
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>Epic Jefferson wrote:
>>>>>> Hey guys,
>>>>>>
>>>>>> updating on this project. I got the pwm shields and i've hit a wall. The
>>>>>> driver circuit I'm using to control the solenoids via arduino is this one
>>>>>> from instructables
>>>>>> (link<http://www.instructables.com/id/Controlling-solenoids-with-arduino/)>)
>>>>>
>>>>>> and
>>>>>> it uses a single pin to control the pwm signal.
>>>>>>
>>>>>> The pwm shield (link<http://www.practicalmaker.com/products/arduino-shields/pwm-shield-assembled>)
>>>>>
>>>>>> is
>>>>>> based on the tlc5940 which requires each pin to have it's own ground
>>>>>> instead of a common ground across all drivers. This is a problem because
>>>>>> all of the information i've found suggest that the signal from the pin
>>>>>> controls the gate (transistor - TIP102). But i think, in the case of the
>>>>>> tlc5940, the 5v supply is constant and the ground is being controlled,
>>>>>> that's why it works perfectly for LED's but seems to be ill suited for this
>>>>>> circuit.
>>>>>>
>>>>>> Any suggestions on how to modify the instructables circuit for use with the
>>>>>> shields? or would the circuit have to completely change?
>>>>>
>>>>>
>>>>>_______________________________________________
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>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>-- 
>>>>www.epicjefferson.com
>>>>www.avmachinists.org Puerto Rico based Art Collective/ Non-Profit Org 
>>>>_______________________________________________
>>>>Pd-list at iem.at mailing list
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>>>>
>>>>
>>>
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>>>
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