https://jrtwine.com/Projects/LVR/ 2026-09-16T19:13:00+00:00 https://jrtwine.com/Projects/LVR/ https://jrtwine.com/Projects/LVR/lib/exe/fetch.php?media=logo.png text/html 2020-05-29T20:19:58+00:00 Anonymous (anonymous@undisclosed.example.com) https://jrtwine.com/Projects/LVR/doku.php?id=assembly&rev=1590783598&do=diff Assembling the Device The LVR and LVR Custom PCBs are very easy to assemble together. All you need is a 40-pin socket for the CPU, a 14-pin socket if you need the inverter to be installed, the DS1233 device and two 20-pin strips for the device connection to the board's CPU socket. The 40-pin socket should be a text/html 2020-05-24T21:42:51+00:00 Anonymous (anonymous@undisclosed.example.com) https://jrtwine.com/Projects/LVR/doku.php?id=configure&rev=1590356571&do=diff Configuring the Custom Circuit The LVR Custom PVB might look a little busy, but configuring it is pretty simple. First, you need to determine of the target CPU's reset line is active high or active low, this is, RESET or /RESET. If it is active low, you do not need to install the 4096 inverter, but you will if the target CPU's reset signal is active high. text/html 2020-05-20T19:36:04+00:00 Anonymous (anonymous@undisclosed.example.com) https://jrtwine.com/Projects/LVR/doku.php?id=examples&rev=1590003364&do=diff Examples Some examples of where the LVR and LVR Custom devices may be useful. The primary use and reason for the creation of the LVR circuit in the first place was to help prevent CMOS corruption on Williams 6809-based hardware that is using a switcher instead of the linear power supply. Once the supply voltage drops during power-down, the LVR device will put the CPU into reset before the voltage hits the point where it would normally cause the CPU to start executing random write operations. … text/html 2020-05-20T16:43:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://jrtwine.com/Projects/LVR/doku.php?id=history&rev=1589993023&do=diff History People have been replacing failing linear power supplies with switchers for years, at least as far back as the RGVAC days, so this is nothing new. People would also do this to the 6809-based Williams hardware (Stargate, Robotron, etc.) with success but would complain about occasional loss/corruption of CMOS memory (settings and bookkeeping information). Someone eventually figured out that the reason was because of how the old linear supply worked alongside the board's CMOS write prote… text/html 2020-05-26T21:59:20+00:00 Anonymous (anonymous@undisclosed.example.com) https://jrtwine.com/Projects/LVR/doku.php?id=introduction&rev=1590530360&do=diff Introduction The LVR Circuit device is a simple CPU supervisor device that will keep a CPU in reset until supply voltages have come up to a suitable level for a short amount of time, and will also put a running CPU into reset if the supply voltage drops too low. text/html 2020-05-20T18:59:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://jrtwine.com/Projects/LVR/doku.php?id=start&rev=1590001154&do=diff JRTwine Low Voltage Reset Circuit This is the page/wiki for the JRTwine LVR Circuit. It will contain information on the LVR device (hereafter referred to as the device) as well as examples of its usage, how to assemble the device, and then how to configure the Custom version of the device, if applicable. Maybe have a look at its