I have some heaters (something like a halogen bulb) that I can't pulse via SSR like I usually would. Instead of glowing at full brightness for x% of the time, I need them to glow at x% brightness. In theory, sufficiently fast frequency will accomplish that fine, but the SSR's typical 8ms on/off limits the period to a large fraction of a second.

Is there a device that I could use that would function more like an electronically controlled variac? Something I can feed a 4-20ma/10v signal and it would output either a %of max voltage or % a much larger current (around 20A)?

Thanks in advance.