#### RANJIHELLO

Joined Jun 20, 2017
11

Base Control switches from 0 to 5V

Transistor Data: Beta =100, Vce (Sat) = 0.3V, Vbe(Sat) = 1.2V (Max); IC(Max) = 1 A

Relay Data: coil 12V, impedance 300 ohm

Calculate:

1. R1?

2. Power dissipation when transistor ON

3. Find base voltage, base current, collector voltage, collector current

4. What is the purpose of D1?

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#### Alec_t

Joined Sep 17, 2013
13,151
Is this school/college Homework/project?
D1 may be in the wrong place. A diode should be in parallel with the relay coil, to catch inductive spikes when the relay switches off.

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#### AnalogKid

Joined Aug 1, 2013
10,125
DECELL - as this obviously is a homework question, the process is to let the TS show his work and justifications first, then comment and advise without just giving away the answers.

<MOD NOTE> The offending post has been deleted </MOD NOTE>

AND, there is nothing wrong with the placement of D1 because we don't know the context of the question. If the base voltage is 5 Vacrms, D1 is required to protect the transistor.

ak

Last edited by a moderator:

#### Alec_t

Joined Sep 17, 2013
13,151
we don't know the context of the question. If the base voltage is 5 Vacrms, D1 is required to protect the transistor.
Good point.