ELF Pre-Amp partial kit
Being new to the group and ELF/VLF in general, I was impressed with the simplicity of Peter’s (VK2AN) ELF pre-amp circuit he posted in the vlf.io group. I contacted him and asked if I could make a partial kit available to the interested community. After many emails, he helped me to to understand the unique orientation and requirements of mounting the LMP7721 OpAmp on a pcb.
This board is basically Peter’s posted circuit, with an 50/60Hz Twin “T” notch filter to filter out domestic supply interference, between the antenna, and his circuit that can be optimized for 60Hz or 50Hz, depending on your local supply frequency. The filter can be bypassed if desired. The pre-amp can be used portable with the 9V battery or hard wired in a remote installation. The balanced audio output is via an RJ54 connector for a cat5 run to your sound card.
Due to the present shipping difficulties for international enthusiasts, and the ability to send this in an envelope, it is only offered as a partial kit that includes the PCB, LMP7721 OpAmp, 1G ohm resistor, and the neon bulb. Most all the other components are common parts and may be already in your inventory, or readily available from your suppliers.
Click here for the assembly manual
