120V heater pad

Pad

• Amazon $20 - [1]
• Ebay $15 in 4 quantity - [2]
• $13 from China - [3]

Resistors

• Use resistors instead - [4]

Halogen As Heater

• Halogens are about 85% heaters.
• For 3D printers, use a 240V bulb, run it at 1/4 power with 120V (P~I^2R) so it doesn't burn out with on-off cycling - by running it only at a fraction of its rated power.
• Use a holder - 4.69 or 4-11/16" holder, for a 240V T3 bulb. [5]
• R7S is the style of holder -[6]
• This bulb is T3 R7S, 118 mm long - [7]
• 1500/375W 240/120v - [8]
• Or use 2 120V 500W in series, more even bed heating, using 2 bulb holders - [9]