Does the light have to be a big brooder type light bulb? Or can it just be a regular 75-100 watt bulb in a regular socket? I was planning on using a lamp kit to make the heat source like in the homemade incubator. Would that work?
You would want to try it out first to make sure that a temperature of 95 degrees can be maintained under the bulb with the ability of the chicks to move to a cooler area if they need to.
Make sure the desk lamp is designed for the size wattage of bulb you are going to use.
Lastly, if you are going to use a 'regular' bulb, don't skimp and get the cheapest bulb. You don't want a cheap bulb burning out/dying on you and your chicks getting chilled. Using red bulbs should allow the chicks to sleep better and to pic at each other less.
A desk lamp could work. It might get so messed up you would never be able to put it back in your room. Make sure it is secured so they cannot knock it over. Arrange it so they cannot get it wet. Depending on litter, the brooder might get dusty which could short out any light. Check often and keep it clean. The dust could short it out or cause the switch to not work.
You can vary the heat by using different wattage of bulbs but be careful not to exceed the capacity of the fixture. You create a fire hazard and also burn up the wiring inside the fixture if you put too strong a bulb in. And if you use reflectors, make sure the reflectors don't cause the light fixture to get too hot.
I have used a 60 watt indcandescent bulb in my brooder lamp no problem. I have covered my brooder with a blanket on really cold nights to keep the warmth in the brooder or tractor. I have a wireless digital thermometer in the brooder or tractor, to monitor the temp. The thermometer has an alarm built in. The alarm will sound if it gets colder than whatever temp I set.