And finally, interconnection schematic to help you to "implant" OMNI protector into an average amplifier. Please note some differences between circuit, PCB and interconnection schematic. OMNI "survived" seven revisions with different PCB-s for different requirements. In some earlier versions, speaker relay was not on the PCB, hence, I needed pins 15 & 16 which do not exist on the board I posted here, which has relays built in. Simply, ignore (do not use) pins 11, 15 & 16. They are already connected within the board. Values of resistors marked with ( * ) are dependable on supply voltages of your amp, and you will have to calculate them for your particular case, by simply using Ohm's Law.
After several E-mails with requests for some explanations regarding operation of particular subsystems within OMNI protector, I've decided to write as short and condensed description as I can. It should be sufficient for maybe even more than basic understanding of how OMNI works. It is ZIP-ed and attached with this post.
It's a 3-day holiday weekend here in the US, so I am assuming that accounts for the lack of response. Everyone leaves early for the holiday on Friday. I only have a few minutes to check up on things here before company arrives. I'll read it all sometime though! All the work is appreciated...
HELLO for all DIY members!
Dear Boraomega
This is my entry here in this FORUM . I didn't know what amplifier to build for me. Now I know -It's LEACH . And after I saw your's PCB for it , I decided. Thank you! I like it very much.
.It isn't quite compact as Leach's original PCB , but it is good for plastic output transistors.
Dear Boraomega
This is my entry here in this FORUM . I didn't know what amplifier to build for me. Now I know -It's LEACH . And after I saw your's PCB for it , I decided. Thank you! I like it very much.
.It isn't quite compact as Leach's original PCB , but it is good for plastic output transistors. 
Well "rlg_200",
If you look at the schematic, you will notice that D10 (coming from Aux. input) is connected to the same point and the same way as D3 and D4. From the previous explanation (zipped and posted several posts before in this thread) and by looking at the schematic, it should be quite easy to see that when AUX input is shorted to ground, it will activate protection. So, that input can be used for anything you want or find useful as an additional control like thermal or over-voltage or "something else" protection. All that is necessary is to provide that your additional circuit (when activated) is shorting AUX input to ground. You can also add some more AUX inputs the same way !!!
If you look at the schematic, you will notice that D10 (coming from Aux. input) is connected to the same point and the same way as D3 and D4. From the previous explanation (zipped and posted several posts before in this thread) and by looking at the schematic, it should be quite easy to see that when AUX input is shorted to ground, it will activate protection. So, that input can be used for anything you want or find useful as an additional control like thermal or over-voltage or "something else" protection. All that is necessary is to provide that your additional circuit (when activated) is shorting AUX input to ground. You can also add some more AUX inputs the same way !!!
Hi boraomega,
Many Thanks for ur reply, Now I know why u call this protection is a universal protection, becuase it protect the amp at thermal runaway, shorted amp, and even over voltage swing.
I have another question if u dont mind, according to the protection if load impedance is below 3.3 ohms the universal protection will react, meaning to say speaker will isolate to the amp. therefore there is no possilble to connect in 2 ohms load speaker, is there any another alternative value of resistor in op-amp to produce 2 ohms load speaker? what is the value of resistor if my voltage supply rail is +/- 70 volts?
rlg
Many Thanks for ur reply, Now I know why u call this protection is a universal protection, becuase it protect the amp at thermal runaway, shorted amp, and even over voltage swing.
I have another question if u dont mind, according to the protection if load impedance is below 3.3 ohms the universal protection will react, meaning to say speaker will isolate to the amp. therefore there is no possilble to connect in 2 ohms load speaker, is there any another alternative value of resistor in op-amp to produce 2 ohms load speaker? what is the value of resistor if my voltage supply rail is +/- 70 volts?
rlg
Hi rlg_200
If you look at the schematic around IC1 area, you will notice that both +IN (pins 3&5) are connected together and their potential is determined by voltage divider 15k/3,3ohm. That resistor 3,3ohms (3E3) is the one that determine minimal impedance (actualy resistance) of the load that will be allowed to be connected without "reaction" by OMNI. Hence, if you need to use lower impedance loads like 2 ohms, you have to lower the value of that resistor to about 1,8 ohms. Take great care about "silent warning" in AndrewT's post!!! Amp safely running 2 ohms with +/-70V supply has to be a "hell of a machine"!!! Obviously, AndrewT know very well why he is "warning" you! Generally speaking, people are frequently very relaxed in that "power-- supply voltage-- load" juggling. Real world loads are 99% EVERYTHING else, but resistive!
If you look at the schematic around IC1 area, you will notice that both +IN (pins 3&5) are connected together and their potential is determined by voltage divider 15k/3,3ohm. That resistor 3,3ohms (3E3) is the one that determine minimal impedance (actualy resistance) of the load that will be allowed to be connected without "reaction" by OMNI. Hence, if you need to use lower impedance loads like 2 ohms, you have to lower the value of that resistor to about 1,8 ohms. Take great care about "silent warning" in AndrewT's post!!! Amp safely running 2 ohms with +/-70V supply has to be a "hell of a machine"!!! Obviously, AndrewT know very well why he is "warning" you! Generally speaking, people are frequently very relaxed in that "power-- supply voltage-- load" juggling. Real world loads are 99% EVERYTHING else, but resistive!
High resolution component placement
Dr Bora (baraomega), can I have copies of the high resolution GIF component placements for your version of the Leach amp, for both the MT200 and TO247 versions? Thanks. My email is wongvuikongat yahoodot comdot my. Thanks.
PS: Remove and replace the words "at" with "@", "dot" with ".". No spaces.
Dr Bora (baraomega), can I have copies of the high resolution GIF component placements for your version of the Leach amp, for both the MT200 and TO247 versions? Thanks. My email is wongvuikongat yahoodot comdot my. Thanks.
PS: Remove and replace the words "at" with "@", "dot" with ".". No spaces.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.