Power supply...
Hi,
Can some one specify a suitable 15V supply for this project ? Can we use the supply designed for Bugle phono stage (http://www.hagtech.com/pdf/powersupply.pdf) ?
Best regards,
Bins.
Hi,
Can some one specify a suitable 15V supply for this project ? Can we use the supply designed for Bugle phono stage (http://www.hagtech.com/pdf/powersupply.pdf) ?
Best regards,
Bins.
Attachments
I'm gonna make you work. Look up the current for your opamps, then the current used by the feedback and load resistors for a full rail voltage across them. Add in whatever panel LEDs and such you might have. My guess is it's way less than an amp. Then use the above advice and use the adjustable regulators. They're truly much better. Unless you have some odd discharge risk, you can eliminate the protection diodes in the schematic above. There are a couple power supply utilities you can search for- makes selecting a transformer and such much easier.
Simple +/-15V supply using TI's uA7815 chips.
Hi CH,
I have found a +/-15V power supply application diagram using TI's uA7815 positive voltage regulators (http://focus.ti.com/lit/ds/symlink/ua7805.pdf). It seems pretty simple with around 1.5A current capability. I am having few of them readily available with me. Please comment.
Best regards,
Bins.
Hi CH,
I have found a +/-15V power supply application diagram using TI's uA7815 positive voltage regulators (http://focus.ti.com/lit/ds/symlink/ua7805.pdf). It seems pretty simple with around 1.5A current capability. I am having few of them readily available with me. Please comment.
Best regards,
Bins.
Attachments
That's the generic fixed supply you'll find everywhere. It should work fine, but you can do a little better if you're willing to add the few resistors needed to use adjustable regulators. There's no requirement for the + and - to be exactly equal, and you may set the adjustable regs to the same voltage as the fixed regs, but the adjustable parts are usually lower in noise and have better specs, especially if you bypass the adjustment pins with some capacitance.
CH
CH
yes; but LT1028 is irrelevant for phono preamps, according
to LT own datasheet, as it s optimal only for low impedance sources...
i would go for a HA12017, as it has a +-26 V supply
limit, thus allowing an extended dynamic range....
noise is 0.185 uV , i.e , 1.3 nV/sqr hz...
Depends on your cartridge for old style MM you need FETs and the AD745 can't be beat(IC's that is) for noise. Read the 1977 National app note on the effects of current noise in phono preamps.
the datasheet says 2.9 nV/sqr hz at 10 khz, 0.29 uV...
at 20kHZ, these value are logically greater...
not unbeatable..the hitachi device is better...
why would this current exist on others devices, and not in the ADI one..
as you say, " current noise into TYPICAL MM inductance"..
I assume this current would be only for direct coupled input,
with no caps to stop dc....
i have trouble understanding, perhaps you could shed
some lights on the subjects..
the ad745 is a jfet input device, so the current noise is "irrelevant" for the mm application.
another approach that was popular in some nice preamps in 70's and 80's is using a pair of low noise jfets as a diff amp feeding a bipolar transistor input op amp.
mlloyd1
(who has also happily used the ad745 in mm phono preamps)
another approach that was popular in some nice preamps in 70's and 80's is using a pair of low noise jfets as a diff amp feeding a bipolar transistor input op amp.
mlloyd1
(who has also happily used the ad745 in mm phono preamps)
The old 5534 with the input disabled and a couple of FET's at the input probably still makes a pretty good preamp. My latest conundrum is the low output Grados with 2 Ohms DC but 2mH they are 125 Ohms at 10k and don't match well with bi-polar devices like real MC's.
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