122-28176 Parallax Inc, 122-28176 Datasheet - Page 213

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

The resistor is 100 Ω ½ watt. The "power rating", ½ watt, means how much heat it can
dissipate before becoming hot enough to damage it with long-term continuous use. With
a 9 V supply, the resistor will be dissipating more heat than it is rated for:
This is almost twice the rated power of the device. As such, the resistor will get very hot
and may discolor with prolonged use.
Additional Parts Required
(1) 2N3904 Transistor - BJT
(1) BS170 Transistor – FET
(1) 220 Ω Resistor
(2) 1 kΩ Resistors
(1) LED
(1) 100 Ω ½ W Resistor (Heater)
(1) 12 V Fan
(1) Polystyrene Test Tube
(1) 9 V battery (not included)
√
√
√
√
√
P = V
If you are using a wall-mount power supply, disconnect it from your board
Construct the circuit in Figure 6-17. The heating resistor (100 Ω ½ watt, R3)
needs to have one lead tightly bent in a U-turn so it can stand vertically up from
the board.
Place the plastic test tube on the breadboard directly over R
Place the fan approximately 3 inches from the incubator so the fan will blow
towards the incubator, as shown in Figure 6-19. (The fan is facing the opposite
direction than it was in previous chapters.)
Connect the 9 V battery to your board.
WARNING: Do not use an unregulated 9 V wall-mount power supply for this activity.
Use a fresh 9 V battery (this activity will drain the battery). The resistor will reach
temperatures high enough to melt soft plastic.
incubator circuit. Do not allow the test tube to touch the resistor directly; even so, it
may warp. NEVER LEAVE POWERED CIRCUITS UNATTENDED!
2
/R = (9V)
2
/100 Ω = 0.81 W.
Use care when constructing the
3
and the LM34.