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Why do they still try to obfuscate the chip numbers? It's not like it's going to stop anyone from reversing the scheme. Those who are familiar with metal detector schematics would pretty much be able to call out a dual opamp vs a quad, likewise a dual comparator vs a quad, depending on the location in the circuit. Then of course the obligatory cmos switches. Maybe some inverters and some counters, it ain't rocket science.
You can pretty much determine what type of chip based on reverse engineering circuit/components around it, so whats the big deal? It then becomes a question of which specific opamp. That can easily be determined by engineer with right type of equipment. Also the rail/power supply pins on any chip is a dead giveaway. This alone narrows things down considerably(certain classes of chips have different vcc/vce ground pinouts). Also, the underbelly of chip can give you big clue as to manufacturer, as there is often some mark there which is specific to a particular brand/manufacturer or company.
An engineer could run checks of pin outs of chip, while the circuit is operational, scoping the pins, looking for tell tale signs of function of the chip(waveforms or pulses).
It is easy nowadays to determine the electrical characteristics of most opamps because very good equipment is now affordable to the masses. Then its just a question of a good cross reference database and some clever tricks, but somebody who is experienced with opamp design would recognise it right away if he has used such a device in the past.
Scratching the name of any chips isn't going to stop even the casual hobbyist nowadays, far less the competition.
You can pretty much determine what type of chip based on reverse engineering circuit/components around it, so whats the big deal? It then becomes a question of which specific opamp. That can easily be determined by engineer with right type of equipment. Also the rail/power supply pins on any chip is a dead giveaway. This alone narrows things down considerably(certain classes of chips have different vcc/vce ground pinouts). Also, the underbelly of chip can give you big clue as to manufacturer, as there is often some mark there which is specific to a particular brand/manufacturer or company.
An engineer could run checks of pin outs of chip, while the circuit is operational, scoping the pins, looking for tell tale signs of function of the chip(waveforms or pulses).
It is easy nowadays to determine the electrical characteristics of most opamps because very good equipment is now affordable to the masses. Then its just a question of a good cross reference database and some clever tricks, but somebody who is experienced with opamp design would recognise it right away if he has used such a device in the past.
Scratching the name of any chips isn't going to stop even the casual hobbyist nowadays, far less the competition.
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