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Old 10-21-2011, 05:01 PM
InactiveX InactiveX is offline
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Join Date: Oct 2011
Posts: 4
Default Alternative Method To Disable Power-Off

I was having some trouble getting my MIDISpeak working in a Speak & Read that I bought. I couldn't initiate the MIDISpeak because the keys wouldn't respond properly. Realising that the key lines 1 and 3 were causing the problem, I disconnected them. This, however, resulted in the S&R powering down after a few minutes (the power save feature). So I deduced that 1 and 3 control the MIDISpeak's disabling of the automatic power down.

After poking around in vain for suitable pins to connect lines 1 and 3 to, I decided to try something else.

I built a circuit that would disable the power down itself, without lines 1 and 3 needing to be connected. An astable was constructed using a 555 timer, which controlled an LED. The LED was set to flash for five seconds every minute or so.

Whilst poking around earlier, I had realised that pins 3 & 4 on the keypad connector in my S&R would simulate a "#/Module Select" keypress. This was a key that, if pressed, would not interfere with the MIDISpeak's operation. Knowing this, I placed a light-dependent resistor across pins 3 & 4.

The LED was placed next to the LDR, and shrouded in black tubing to prevent light getting in. This formed a vactrol, used to simulate the # keypress when the LED is lit every minute or so.

The Speak & Read stays on and all the buttons work. Everything is powered by the S&R's batteries.

I can now rock out on my S&R all night long.

(Well, for longer than 4 minutes, anyway. )
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Old 10-26-2011, 04:31 PM
John's Avatar
John John is offline
Join Date: Jan 2009
Posts: 3,007

Hi InactiveX, welcome and thank you for this contribution.
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Old 12-13-2011, 09:43 AM
InactiveX InactiveX is offline
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Join Date: Oct 2011
Posts: 4

Cheers John!

Here's a diagram of the circuit:

R1 = 68K
R2 = 680K
C1 = 100μF
C2 = 0.01μF

As described above, the LED should be placed next to a light-dependent resistor. The two pins on the LDR should be connected to pins on the Speak to simulate the keypress (this will vary between versions - you will have to poke around to find a keypress that is suitable and doesn't interfere with operation).

It is fine to use the standard Speak battery power (6V) to power the circuit.

Last edited by InactiveX; 12-13-2011 at 10:06 AM.
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