122-28176 Parallax Inc, 122-28176 Datasheet - Page 146

• 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

But before testing this out, let's ensure the devices can meet the specifications with the
fan acting as the load.
The BASIC Stamp can easily handle the base current required. Taking into account good
engineering practices of working under worst case conditions and driving the devices to
only ½ to ¾ their maximum rating, the specifications look good for drive control.
Parts Required
(1) Resistor – 100 Ω
(4) Resistors – 220 Ω
(1) Resistors – 1 kΩ
(1) Opto-Reflective Switch – QRB1114
(1) LED - Red
(2) NPN Transistors – 2N3904
(1) Brushless DC Fan
(1) BS170 MOSFET Transistor
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Q. Can the transistor collector handle the current requirements of the fan, which
is 90 mA?
A. Yes, the 2N3904 is rated for 200 mA continuous.
Q. Can the transistor handle the collect-emitter voltage required by the fan,
which is 12 V?
A. Yes, the 2N3904 is rated for 40 V
Q. Can the BASIC Stamp provide sufficient base current to drive the collector
at 90 mA?
A. With a minimum h
Build the circuit shown in Figure 5-2 and Figure 5-3, leaving the ADC circuit on
the board for later use. Set aside the BS170 MOSFET transistor for the moment.
I
B
= I
C
/h
FE
= 90 mA/100 = 0.9 mA
FE
of 100 for the 2N3904:
CE
.