Snap Circuit Kits | Learn Electronics & Electricity Safely

Snap Circuits made electronics engineering easy. You dexterously design, build, analyse and draw schematic like a pro! It is a playful tool that will equally engage kids, hobbyists, young and beginners to electronics and electricity. They will build strong foundations to circuit designing. These are not kits but they have a small science lab in a box. Above all, they are safe, no harm to kids if they are around.

There are many snap circuit kits available, but I try to curate those kits only which are under $75. 

Elenco Practical Soldering Project Kit:

The kit includes soldering practice boards and materials. It is a trouble-free soldering kit. Soldering has to be learnt and done by electronic technicians, students and hobbyists. It provides better practicing  material with simple projects. With the help of this kit you will gain knowledge about the following topics.

• Soldering. How to solder

• Multivibrator

• Experience with Printed Circuit Boards

• Two tone European siren

Snap Circuits “Arcade”, Electronics Exploration Kit:

The kit contains base and column grids that function like the printed circuit board.

With the help of this kit you will get to know about 200 different projects.

• Preprogrammed microcontroller with many innovative ways and ideas to explore

• Get an understanding of electricity and electronics engineering, circuitry

• 
  

Snap Circuits Green Alternative Energy Electronics Exploration Kit

I recommend you to buy this kit. You will learn about alternate ways of energy. What is meant by green energy? What are different sources of energy? The best of all, this is compatible with other kits as well. The power produced by this kit can be used to power other kits as well. The best kit to get firsthand experience with 

• Solar energy

• Wind energy 

• Hydroelectric power

• Rechargeable batteries

• 

Snap Circuits 3D Illumination Electronics Exploration Kit:

Electronics and electricity concepts become easier with the help of snap circuit kits. It combines knowledge, creativity, practical experience in  attractive and innovative ways. Each kit is provided with illustrated manuals. Follow instructions and build over 150 projects.

• 3-Color Light Tunnel

• Exciting light effects

• Projector with 6 cool images

• Mirrors and Reflecting circuits

• Unique 3D design

Snap Circuits - 3D M.E.G. Electronics Discovery Kit:

M.E.G. (Magnetics-Electronics-Gears) kit introduces electricity, engineering and circuitry. It comes with building blocks with snaps to make 3D structures like those found in real Life life.

3D M.E.G. Kit

Snap Circuits Snapino - Making Coding A Snap

Getting started with Arduino with snap circuit SNAPINO. It is compatible with Arduino and other snap circuit kits.

This kit introduces open source Arduino, it's coding, prototyping. It is provided with the well written instruction manual.

Collector Feedback Bias - AC | DC Load Line & Q Point Calculations

Learning Objectives:

• What is collector feedback bias?
• Evaluate Q point, AC load line, DC load line
• How to select Q point according to the application?
• Centred Q point
• Q point near saturation
• Q point near the cutoff 
• Maximum possible peak to peak voltage

This topic helps you to design collector feedback bias circuits.

This is another biasing technique of BJT based circuits. In this technique, a resistor is connected in between base and collector terminals. The collector terminal provides biasing voltage for the base emitter terminal. 

There are a similar number of components required as it is in base bias. But it is far more stable than the base bias circuit. The circuit has better stability that is thermal or bias stability. 

The important aspect of this bias is that it is designed to work only in the active region.

Fig 1: A Collector feedback bias

DC Load Line:

KVL at the output circuit.

-VCC + ICRC + IBRC + VCE = 0 ..eq 1

IB = IC/β

Substitute IB, equation 1 becomes

-VCC + ICRC + (IC/β)*RC + VCE = 0

-VCC + ICRC (1+ 1/β) + VCE = 0..eq2

Substitute VCE = 0 in ..eq2

VCC = ICRC(1+1/β)

IC = VCC/RC(1+1/β)

With the help of approximation 1+1/β = 1

IC = VCC/RC ..eq3

Substitute IC = 0 in ..eq2

VCE = VCC ..eq4

Q Point (VCEQ , ICQ):

Apply KVL to the input circuit.

-VCC + ICRC + IBRB + VBE = 0 ..eq5

IB = IC/β

Substitute IB and solve for IC

-VCC + ICRC + ICRB/β+ VBE = 0

-VCC + IC(RC + RB/β)+ VBE = 0

ICQ = (VCC - VBE) / (RC + RB/β)..eq6

KVL at output circuit.  

-VCC + ICRC + IBRC + VCE = 0 ..eq7

IB = IC/β

Substitute IB and solve for VCE

VCE = VCC - ICRC - ICRC/β

VCE = VCC - ICRC(1+ 1/β)

1+1/β ~ 1

VCEQ = VCC - ICRC..eq8

AC Load Line:

I am not going into the details of AC load line. 

iC(sat) = ICQ + VCEQ/rC..eq9

vce(cut) = VCEQ + ICQ*rC..eq10

Example 1: RB = 40k

Step 1: DC Load Line

From eq3 and eq4

VCE = 10V

IC = 10mA

Step 2: Q Point (VCEQ , ICQ)

From eq6

ICQ = (VCC - VBE) / (RC + RB/β)

ICQ = (10 - 0.7) / (1k + 40k/100)

ICQ = 6.6mA

From eq8

VCEQ = VCC - ICRC

VCEQ = 10 - 6.6m*1k

VCEQ = 3.4V

Step 3: AC Load Line

From eq9

iC(sat) = ICQ + VCEQ/rC

iC(sat) = 6.6m + 3.4/500

iC(sat) = 6.6m + 6.8m

iC(sat) = 13.4mA

From eq10

vce(cut) = VCEQ + ICQ*rC

vce(cut) = 3.4 + 6.6m*500

vce(cut) = 6.7V

Step 4: Maximum Peak To Peak Voltage:

It is also called output compliance. I discussed it in detail in base bias analysis.

We will check for both compliances. Amplifier compliance will be the smaller value.

PP =2* VCEQ = 6.8V

PP = 2*ICQ*rC = 6.6V

Since the Q point is almost in the middle of the AC load line. Hence both compliances are almost the same. It is also visible in the figure below

Fig 2: Example 1

Example 2: RB = 100k

Step 1: DC Load Line

From eq3 and eq4

VCE = 10V

IC = 10mA

Step 2: Q Point (VCEQ , ICQ)

From eq6

ICQ = (VCC - VBE) / (RC + RB/β)

ICQ = (10 - 0.7) / (1k + 100k/100)

ICQ = 4.65mA

From eq8

VCEQ = VCC - ICRC

VCEQ = 10 - 4.65m*1k

VCEQ = 5.35V

Step 3: AC Load Line

From eq9

iC(sat) = ICQ + VCEQ/rC

iC(sat) = 4.65m + 5.35/500

iC(sat) = 4.65m + 10.7m

iC(sat) = 15.35mA

From eq10

vce(cut) = VCEQ + ICQ*rC

vce(cut) = 5.35 + 4.65m*500

vce(cut) = 7.6V

Step 4: Maximum Peak To Peak Voltage:

We will check for both compliances. Amplifier compliance will be the smaller value.

PP =2* VCEQ = 10.7V

PP = 2*ICQ*rC = 4.65V

Output compliance is the smaller value and hence it is 4.65V. Or you can say maximum peak to peak voltage swing should not be greater than 4.65V.

Fig 3: Example 2

Example 3: RB = 150k

Step 1: DC Load Line

From eq3 and eq4

VCE = 10V

IC = 10mA

Step 2: Q Point (VCEQ , ICQ)

From eq6

ICQ = (VCC - VBE) / (RC + RB/β)

ICQ = (10 - 0.7) / (1k + 150k/100)

ICQ = 3.72mA

From eq8

VCEQ = VCC - ICRC

VCEQ = 10 - 3.72m*1k

VCEQ = 6.28V

Step 3: AC Load Line

From eq9

iC(sat) = ICQ + VCEQ/rC

iC(sat) = 3.72m + 6.28/500

iC(sat) = 3.72m + 12.56m

iC(sat) = 16.28mA

From eq10

vce(cut) = VCEQ + ICQ*rC

vce(cut) = 6.28 + 3.72m*500

vce(cut) = 8.14V

Step 4: Maximum Peak To Peak Voltage:

We will check for both compliances. Amplifier compliance will be the smaller value.

PP =2* VCEQ = 12.56V

PP = 2*ICQ*rC = 3.72V

Output compliance is the smaller value and hence it is 3.72V. Or you can say maximum peak to peak voltage swing should not be greater than 3.72V.

Fig 4: Example 3

Conclusion:

You have observed the different values of RB and Q point position on the load line. Q point remains in the active region for a wide range of RB. In collector feedback bias, as you decrease RB, the Q point shifts towards saturation but doesn't reach the saturation region.