P
Phil Allison
Guest
Hi to all,
I have a near new, Fender " Deluxe Reverb-Amp " on the bench.
This is a so called " Reissue " of a 22watt, all valve guitar amp first sold
back in 1965.
The circuitry is identical to the original except for one low cost component
that has been substituted .... like Vince Sorrenti famously says: I see
it, but I doooaann believe it !!!!
Inside the amp's chassis has been fitted an SMD board, about 50mm x 100 mm,
that does just *one* job - it replaces the usual CdS photo cell in the
tremolo circuit !!!!!
On the back of the SMD board, in copper, it says " ROHS TREMOLO ".
The 12AX7 valve responsible for the tremolo effect is still fitted and fully
wired - but the connections that usually go to the Ne2 lamp and the CdS
cell are now routed the SMD board instead.
The main IC on the SMD board is an LM13700 transconductance amp - plus a
TL072 and numerous transistors, caps etc. It does the job of mimicking the
CdS characteristic rather well.
But WHY ??
How much EVIL cadmium is inside one, tiny CdS cell ??
Remember: NiCd batteries are still being sold and still fitted to many power
tools - even in Europe.
How completely bonkers !!!!
..... Phil
I have a near new, Fender " Deluxe Reverb-Amp " on the bench.
This is a so called " Reissue " of a 22watt, all valve guitar amp first sold
back in 1965.
The circuitry is identical to the original except for one low cost component
that has been substituted .... like Vince Sorrenti famously says: I see
it, but I doooaann believe it !!!!
Inside the amp's chassis has been fitted an SMD board, about 50mm x 100 mm,
that does just *one* job - it replaces the usual CdS photo cell in the
tremolo circuit !!!!!
On the back of the SMD board, in copper, it says " ROHS TREMOLO ".
The 12AX7 valve responsible for the tremolo effect is still fitted and fully
wired - but the connections that usually go to the Ne2 lamp and the CdS
cell are now routed the SMD board instead.
The main IC on the SMD board is an LM13700 transconductance amp - plus a
TL072 and numerous transistors, caps etc. It does the job of mimicking the
CdS characteristic rather well.
But WHY ??
How much EVIL cadmium is inside one, tiny CdS cell ??
Remember: NiCd batteries are still being sold and still fitted to many power
tools - even in Europe.
How completely bonkers !!!!
..... Phil