[sdiy] NVRAM for TR606?

Maarten Halmans diy at artefacts.nl
Thu Apr 6 07:38:42 CEST 2023

The modification I described earlier works that way. You add an extra 
diode to prevent the lithium cell to be charged. Connect it's cathode to 
the cathode of D38/D39. It is connected to BU in the schematic, from 
this point only the 2 RAM's are powered and IC6 which makes sure the RAM 
is not accessed when the power is off.  You do not need two cells, the 
RAM content is kept perfectly with one cell. Dtata retention level of 
the upd444 is 2.0Volt.


Op 6-4-2023 om 05:49 schreef brianw:
> This is why I mentioned using two diodes. Yes, you have to disconnect the SRAM power pin where it connects to the rest of the instrument power, and then reconnect that with a diode so that power can only flow from the instrument to the SRAM. Meanwhile, the coin cell battery pair have their own diode, to prevent them from being "charged" by the instrument power.
> Brian
> On Apr 5, 2023, at 12:33 PM, Florian Anwander wrote:
>> The standard 606 would be able to run with the batteries too. If you want to avoid that you'd have to remove the corresponding connection to the power-socket.
>> Am 05.04.23 um 20:06 schrieb Gordonjcp:
>>> You're not running the instrument on it, you're just keeping the memory contents alive.
>>> A coin cell will last for years.
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