- High Voltage OP amp - 6 Updates
- backlights #2 - 1 Update
| kayge <kgpupswitch@gmail.com>: Sep 03 06:31PM On Sat, 03 Sep 2022 14:34:44 +1000, Trevor Wilson wrote: > And no, it is not possible to drop the rail Voltages. They must remain > at +/-22 Volts. > TIA Hello, TI's OPA552UA has up to +/-30V rails and a bit better slew rate (24V/uS)although it's a bit noisier. You may find a dual version of this at TI. |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Sep 03 03:06PM -0400 Trevor Wilson wrote: > And no, it is not possible to drop the rail Voltages. They must remain > at +/-22 Volts. > TIA What's the required output swing? A baby board with one or two zeners in the supply leads (plus a 100 nF-ish bypass between them) is pretty easy, at least if you get these things in a lot. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| Trevor Wilson <trevor@rageaudio.com.au>: Sep 04 08:44AM +1000 On 4/09/2022 5:06 am, Phil Hobbs wrote: > easy, at least if you get these things in a lot. > Cheers > Phil Hobbs **I need maximum output Voltage swing. Hence the designer (now deceased) chose a +/- 22 Volt supply. Hence the need for higher Voltage OP amps. -- This email has been checked for viruses by Avast antivirus software. www.avast.com |
| Trevor Wilson <trevor@rageaudio.com.au>: Sep 04 08:56AM +1000 On 4/09/2022 4:31 am, kayge wrote: > Hello, TI's OPA552UA has up to +/-30V rails and a bit better slew rate > (24V/uS)although it's a bit noisier. You may find a dual version of this > at TI. **Thanks for that. I can probably live with a higher noise level. I like the idea of a higher speed OP amp. I found a couple available locally, though there is a long lead time for more. I can live with that. Thanks for the tip. -- This email has been checked for viruses by Avast antivirus software. www.avast.com |
| Phil Allison <pallison49@gmail.com>: Sep 03 05:28PM -0700 Trevor Wilson wrote: ================= > I am servicing a power amplifier which uses a dual, 8 pin DIP OP amp. > Unfortunately, the rail Volts on the OP amp (LF353) is +/- 22 Volts. ** That is a mistake, all versions of the Sumo 9 used nominal +/-20V rails fed from series regs with 20V zeners. > I need a suggested replacement. ** Which MUST be a FET input op-amp. > And no, it is not possible to drop the rail Voltages. **Course it is, they are meant to be 19.5V each anyway. > They must remain at +/-22 Volts. ** Humbug. ..... Phil |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Sep 04 09:56AM -0400 Trevor Wilson wrote: >> easy, at least if you get these things in a lot. > **I need maximum output Voltage swing. Hence the designer (now deceased) > chose a +/- 22 Volt supply. Hence the need for higher Voltage OP amps. Sure, but typically not everything in a circuit needs to swing the full supply range. You're losing at least a couple of V_BEs on each end now--in fact the LF353 datasheet minimum output swing is +-3 V from the rails (+-12 on +-15 supplies) even at light loads. There are nice things in the 40V range such as the MC34072, which typically swings +14 to -14.7 off +-15 if fairly lightly loaded. It's also a lot quieter than the LF353, not that you probably care much in a power amp. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| kayge <kgpupswitch@gmail.com>: Sep 03 06:35PM > just above half to preserve the LED array. If it doesn't have an > adjustable setting in the menu, let me know and I'll show you what > resistor to change to lower the global current. Thanks for all your help my friend, got the backlight issue fixed by jumping around that bad connector, but it doesn't matter if your display is cracked to shit. I had no idea they were so fragile and I even have the thing on a queen bed. I take it any flexing of the display and it's toast. |
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