Hi,
I bought a pair of AOL Sperry LM3875 boards a while back and now cannot locate the schematic to build them. Anyone out there have a copy or have the parts list?
Thanks,
Jeff
I bought a pair of AOL Sperry LM3875 boards a while back and now cannot locate the schematic to build them. Anyone out there have a copy or have the parts list?
Thanks,
Jeff
Sperry Gainclone PCB assembley
Hi I know its one year old but if you are still looking I'm sure I have the original PDF somewhere! Don't worry I not asking for money - its just on another older computer that actually still has a lot of documents I should have salvaged.... 🙂 Answer me by PM if you wish!
:edited by mod to remove email address.
Hi I know its one year old but if you are still looking I'm sure I have the original PDF somewhere! Don't worry I not asking for money - its just on another older computer that actually still has a lot of documents I should have salvaged.... 🙂 Answer me by PM if you wish!
:edited by mod to remove email address.
It is good practice not to publish e-mail addresses in posts for your own safety. You can PM or ask another member to PM.
Or, set up a trash email account like i do....gmail is good for this, you can keep yourprivacy by providing bogus info to open a mail account.....i have two or thee of these....
I sent you an email, i could still use the schema....
I sent you an email, i could still use the schema....
Ha! thankyou Pacificblue for your advice, any way I can get that message edited with the email address replaced with " pm me "? Cannot see any obvious way to to this ....Administrator??!!
AOL Speryy Audio
eleven years later, same problem ;-)
I also have two of those LM3875 PCBs around but no documentation.
Can you please send me a copy.
Regards
Peter
eleven years later, same problem ;-)
I also have two of those LM3875 PCBs around but no documentation.
Can you please send me a copy.
Regards
Peter
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Its not the complete story, I have the assembly instructions scan in pdf but can't upload it - it somehow ended up as 10MB file..... Attached is a poor quality scan you might be able to make out. I'll see what I can do at the weekend, a rescan is in order. You may however have enough clues here to help you. Supply capacitors whatever you can fit at the voltage you are using!!!! 4 off 1,000uF 50V should cover most needs....
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Dear Simon,
this is a very informative and well-written documentation, that can be useful for other chipamp builders too.
I am using the LM3875 PCBs in T-network configuration (inverting amplifier) with tube input buffer and will post my findings.
Regards
Peter
this is a very informative and well-written documentation, that can be useful for other chipamp builders too.
I am using the LM3875 PCBs in T-network configuration (inverting amplifier) with tube input buffer and will post my findings.
Regards
Peter
Tidied up main Sperry document.....
Here is a better copy of the Sperry PCB documentation. If admin wish to remove the previous one to save space that'll inconvenience no-one.....
Here is a better copy of the Sperry PCB documentation. If admin wish to remove the previous one to save space that'll inconvenience no-one.....
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Pieroh,
both the schematics shown for inverting and non-inverting are poor. I would not build in either of those arrangements.
Re-design the component values to better suit the chip after you have decided whether to go inverting or non-inverting.
Those schematics (improved quality in 2nd posting) are from the datasheet and are what the board is based upon. I can attest to having build 2 of these PCBs (and have 4 more) and so far (3 yrs of intermittant, but often, use) have had no problem with them. There were no signs of oscillation and they ran coolish untill I really loaded them with 4 ohms, which is what I expect. They were still however thermally stable at elevated temperature.
They were both fitted on a single heatsink 250mm long x 80mm tall with 50mm long fins, quite a generous surface area, as is best for any chip-amp!
They were both fitted on a single heatsink 250mm long x 80mm tall with 50mm long fins, quite a generous surface area, as is best for any chip-amp!
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