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Hi Group,
Some of you have recieved this board already. I wish to inform you that 1 mod is required. I did not design the 3.3V to 5V circuit well enough and as it turns out, it's not really even needed. The 3.3V data output of the SD Memory Card can be tied directly into the LS TTL input of the 74LS299 shift register. One trace needs to be cut for this mod. I am working on a manual for this board, I plan to publish it later today. But, for now, before you build, you might want to cut this trace. The trace is on the component side, from pin 11 of the 74LS299 chip. Just below the silk screen text "SD LOOP BACK", there is the best place to cut it since there is ample space on either side. See photo attached. A jumper wire then should then be placed between the resistor lead above the silk screen text "R7" to pin 11. Regards, Josh |
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