I am officaly a scientist
Last week I became a scientist.
Sort of...
If you don't remember I'm taking an independent study class I call: introduction to research methods in physiological psychology. Besides being a mouthful it's 2 credits. On Wed. I finally did something in the lab besides talk to my prof and calibrate oscilloscopes. I got to electrocute a piece of 100% cotton string!
A Harvard box is a simple device used to electrocute string or nreves from your favorite beastie. The box consists of a trough for saline (saltwater), some electrodes (wires), and plugs (like for headphones). The electrodes cross the trough over the narrow part parallel to the ground. The electrodes are connected to the plugs, of which there are 3 pairs. The electrodes are not a complete circuit so something needs to connect them for anything electrical to happen.
The trough is filled halfway with saline, the electrodes are not touching the saline. The string is soaked in the saline and placed across all the electrodes. It is very important that the string touch all the electrodes or bad things will happen; like frustration and confusion. To ensure contact with the electrodes I viewed the string under a dissection scope, which is what you see the nerdy guy on CSI using when he looks at hair or fibers. This part is tough because you have to push on the string and bend the wires using a tweezers all while looking in the dissection scope.
After the tediousness I set up the rest of the equipment. To shock the string I used a Grass SD9 stimulator. The stimulator is a device that was used in surgery on human patients during the 70s. What it does is produce electrical pulses that can be controled for duration, frequency, volts,and delay before the first pulse. The voltage that I would be reading off the system is small so I set up an amplifier to magnify the volts by 1000x. Next I set up an oscioolscope to see the voltage. An oscilloscope is basically the gadget that shows heartbeats with a green line and a blip sound.
Once I turned everything on and tested out the setup I found how the system affects the output of the stimulator. If the stimulator was connected directly to the oscilloscope a line with a raised portion would show on the scope. The raised portion looks like [ with the open end connecting to the line. The raised portion represents the jump in voltage caused by the output of the stimulator. When I hooked the stimulator to the Harvard Box the clean table like reading disappeared. What I saw was a pulse of about 2 volts that tapered off to 0 an then an opposite pulse that also tapered to 0. These pulses represented the discharge (first pulse) and recharge (second pulse) of a capacitor in the stimulator. When the duration of the pulse is increased the time in between pulses increases. With an increase in frequency the # of pulses shown in the oscilloscope increases.
This took me about 2 hours to complete. I now know how to use the equipment and I'll be able to progress to living beasts like snails and crayfish. Animals rights activists are gonna hate me...
Sort of...
If you don't remember I'm taking an independent study class I call: introduction to research methods in physiological psychology. Besides being a mouthful it's 2 credits. On Wed. I finally did something in the lab besides talk to my prof and calibrate oscilloscopes. I got to electrocute a piece of 100% cotton string!
A Harvard box is a simple device used to electrocute string or nreves from your favorite beastie. The box consists of a trough for saline (saltwater), some electrodes (wires), and plugs (like for headphones). The electrodes cross the trough over the narrow part parallel to the ground. The electrodes are connected to the plugs, of which there are 3 pairs. The electrodes are not a complete circuit so something needs to connect them for anything electrical to happen.
The trough is filled halfway with saline, the electrodes are not touching the saline. The string is soaked in the saline and placed across all the electrodes. It is very important that the string touch all the electrodes or bad things will happen; like frustration and confusion. To ensure contact with the electrodes I viewed the string under a dissection scope, which is what you see the nerdy guy on CSI using when he looks at hair or fibers. This part is tough because you have to push on the string and bend the wires using a tweezers all while looking in the dissection scope.
After the tediousness I set up the rest of the equipment. To shock the string I used a Grass SD9 stimulator. The stimulator is a device that was used in surgery on human patients during the 70s. What it does is produce electrical pulses that can be controled for duration, frequency, volts,and delay before the first pulse. The voltage that I would be reading off the system is small so I set up an amplifier to magnify the volts by 1000x. Next I set up an oscioolscope to see the voltage. An oscilloscope is basically the gadget that shows heartbeats with a green line and a blip sound.
Once I turned everything on and tested out the setup I found how the system affects the output of the stimulator. If the stimulator was connected directly to the oscilloscope a line with a raised portion would show on the scope. The raised portion looks like [ with the open end connecting to the line. The raised portion represents the jump in voltage caused by the output of the stimulator. When I hooked the stimulator to the Harvard Box the clean table like reading disappeared. What I saw was a pulse of about 2 volts that tapered off to 0 an then an opposite pulse that also tapered to 0. These pulses represented the discharge (first pulse) and recharge (second pulse) of a capacitor in the stimulator. When the duration of the pulse is increased the time in between pulses increases. With an increase in frequency the # of pulses shown in the oscilloscope increases.
This took me about 2 hours to complete. I now know how to use the equipment and I'll be able to progress to living beasts like snails and crayfish. Animals rights activists are gonna hate me...