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74HC04 vs SN7404n notice #2
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the extra 470 ohm resister can be used parallelly on the outer two pin of volume control, make volume adjust more smooth. |
Interesting i had a batch of SN7404n (ordered 5) ..4x worked with 470R. ..but 1x pcb needed both 470 replaced with a 4.7k. I suspect anything above 1k will work more consistently. Note (new builders):
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These values must still be just downright incorrect. This card doesn't work right at all using all original mouser parts linked in the BOM. 1K resistors paired with a 100pf cap generate a TON of random noise and loud glitches and the FM music gets all corrupted at all times. When changing resistors to a higher value, the issue is fixed and I think this card works best with 4.7k resistors. What are these resistors even supposed to achieve and what is the configuration of the original Adlib card? |
a second hand IC maked "sn7404n england" works fine with 470 ohm resister
but a brandly new IC maked "74HC04" from JLC market need a 4.7k ohm resister to work with.
i have no idea about why , just post here for people who might need it.
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