Solenoid Design - MAC valve
MAC Valve solenoids are used in a few markers, first made popular in the AKALMP Excalibur (and later the Viking). Those markers use a four-way MAC 44 series solenoid. Most MAC solenoids of this small size are direct-acting valves, so their dwell times are relatively low, since their airflow spools are quick to shift. For instance the published specs are around 2-3 milliseconds to switch the spool's airflow.
MAC solenoids are often larger than others out there, however they can transfer a large air volume for each cycling and are meant to use 10-32 threaded hose connections. The MAC design has two disadvantages to it, though, and the first is that they aren't very serviceable when it comes to maintenance. The valves consist of a few internal seals that are easy to disrupt, which makes the solenoids quicker to replace as a whole rather than disassemble for parts swap.
The other disadvantage to MAC solenoids is the large amount of power they require. All MAC valves that are small enough to be useful are direct-acting types, meaning there is no go-between pilot between the core and the spool. This, coupled with the design of their spools themselves, requires a large amount of power to cycle the valve for each shot.
Pictured here is the 44 series four-way solenoid, used in the Excalibur, Viking, Rainmaker, and a couple other 2000-era markers.
In 2008 MAC released a new series of smaller valves that are almost half the size of previous 44 solenoids. These new micro valves require even more power to operate, but are still relatively high in airflow. A diagram of a three-way 34 series solenoid can be seen below:
These small 33 and 43 series solenoids are nice and small, and variations are used in some Eclipse markers as of 2008. Lucky Paintball also used them for a brief period of time with their Ion upgrade board (Spitfire), and some other developers are planning on using them in their newer equipment as well. The small size makes them a popular choice by developers.
