K

Displayed in the node picker as just "K", this one does exactly one thing: it holds a float number and outputs it. Functionally it's a primitive float node, the same category of thing as ComfyUI's stock float widget. What it's actually for is the UI, not the math - instead of a slider or a text box, you get a turnable knob you drag in a circle to set the value. If that sounds like a small thing, it is, and that's fine - this node isn't trying to be more than it is.

What it's for

Reach for this when you're building a workflow you want to look like a control panel rather than a graph - a "mixing console" layout where CFG, denoise, guidance, and a few strength values all sit as knobs in a row instead of blending into a wall of sliders. It's cosmetic sugar over a plain float primitive, and it lives in the pack's CRT/Utils/UI category alongside similarly decorative nodes like Fancy Note and a Fancy Timer Node. If you don't care how your graph looks and just want a number, the stock primitive float node does the identical job with zero extra dependency weight. If you do care - streaming your workflow, demoing it to someone, or just enjoying a nicer-looking canvas - this is the node for that.

The input and output that matter

There's exactly one of each:

• value (FLOAT, default 0, range -10000 to 10000, step 0.01) - the number the knob is set to. Drag it, type it, whatever your ComfyUI frontend supports for a float widget.
• One unnamed FLOAT output - wire it into anything that takes a float: cfg, denoise, a LoRA strength, a guidance value, a custom node's threshold input, anything.

That's the entire contract. No min/max exposed per-instance beyond the fixed -10000 to 10000 range, no snapping options, no color coding - it's deliberately minimal.

How to install it

SimpleKnobNode comes bundled inside CRT-Nodes, a large pack (100+ nodes) covering everything from video sampling to color grading to audio tools. Via ComfyUI Manager, search CRT-Nodes and install. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/PGCRT/CRT-Nodes.git
pip install -r CRT-Nodes/requirements.txt

then restart. You'll pull in the whole pack's dependency stack (OpenCV, Ultralytics, librosa, and more) to get one knob widget - that's just how this pack ships, as a single suite rather than a la carte.

Common issues & troubleshooting

There's very little that can actually go wrong with a node this small, but a couple of things are worth knowing:

It's easy to mistake for something with more range control than it has. The -10000 to 10000 bound is hardcoded on this node - if you need a knob clamped to, say, 0 to 1 for a strength value, you'll either need to trust yourself not to drag past the useful range, or clamp the output downstream with a math node.

If it doesn't show up after install, that's almost certainly a CRT-Nodes-wide import failure (a dependency conflict in the pack's shared requirements.txt), not anything specific to this node - check your ComfyUI console for an import error on the package rather than assuming the knob itself is broken. Given how trivial this node's own code has to be, it either loads with the rest of the pack or it doesn't load at all.