owel
Well-known member
Just finished prototyping this little guy tonight. So far, so good with the basic oscilloscope/signal gen/audio analyzer testing.
It's basically a DIP8/SOIC8-Adapter for use as a 990/2520 DOA substitute.
To help the chip you want to use drive more difficult loads, an output line driver stage has been added.
Some comparison readings. Condition: +/-18Volts, 600R load
IC chip only : 0.0038% THD @ 4dBu, f=1Khz; 30K BW
IC chip on DOA-Adpater : 0.0029% THD @ 4dBu, f=1Khz; 30K BW
Look at that, THD got even lower!
The output driver helped achieve this.
SNR and SINAD ratio also increased by a few dB.
Some photos:
With a DIP8 IC socket, and using a National LME chip.
You can also use a SMD SOIC8 chip... (haven't tested this configuration yet, I need to buy/salvage some SOIC chips to use in testing.)
This weekend I'll try driving a real transformer with it (and not just a 600R resistor), plug it into a 512C pre... see how it works out.
You can use the trimmer to adjust how much current you want to feed your line driver. (The transistors will get hotter though as you increase it.)
For example: @ +/-18Volts.
PDIP8 chip only : 6mA
on DOA-Adapter: 11mA @ lowest setting (you can increase this up to 60mA and above... I don't know yet the max. upper limit, don't want to push this 1st prototype too far this early.
** Notice the BYPASS mode? You can solder a chip and a 0R resistor (or jumper) if you don't want to use the line driver output transistors and extra components.
So it will work as a simple straight DIP/SOIC to 990/2520 Adapter.
If this works out, anyone interested in a KIT?
It's basically a DIP8/SOIC8-Adapter for use as a 990/2520 DOA substitute.
To help the chip you want to use drive more difficult loads, an output line driver stage has been added.
Some comparison readings. Condition: +/-18Volts, 600R load
IC chip only : 0.0038% THD @ 4dBu, f=1Khz; 30K BW
IC chip on DOA-Adpater : 0.0029% THD @ 4dBu, f=1Khz; 30K BW
Look at that, THD got even lower!
The output driver helped achieve this.
SNR and SINAD ratio also increased by a few dB.
Some photos:
With a DIP8 IC socket, and using a National LME chip.
You can also use a SMD SOIC8 chip... (haven't tested this configuration yet, I need to buy/salvage some SOIC chips to use in testing.)
This weekend I'll try driving a real transformer with it (and not just a 600R resistor), plug it into a 512C pre... see how it works out.
You can use the trimmer to adjust how much current you want to feed your line driver. (The transistors will get hotter though as you increase it.)
For example: @ +/-18Volts.
PDIP8 chip only : 6mA
on DOA-Adapter: 11mA @ lowest setting (you can increase this up to 60mA and above... I don't know yet the max. upper limit, don't want to push this 1st prototype too far this early.
** Notice the BYPASS mode? You can solder a chip and a 0R resistor (or jumper) if you don't want to use the line driver output transistors and extra components.
So it will work as a simple straight DIP/SOIC to 990/2520 Adapter.
If this works out, anyone interested in a KIT?