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Design for a Radio-Controlled Car

I recently bought my son his first radio-controlled car. Playing with it reminded me how as a young child I loved to get radio-controlled toys so I could tear them open to figure out how they worked. The magic of the electronics is what fascinated me. It was this early curiosity that helped drive me toward a career in electronics engineering.

Unfortunately, I never figured out the details of how one worked. Once I began the serious study of electronics other areas captured my interest. So I decided to take apart my son’s new car to finally see how one worked.

At the heart of the design is a popular transmitter/receiver chip combo, specifically designed for radio-controlled cars, called the TX-2B/RX-2B. This chip pair performs the data encoding and decoding. All other functions, including the transmitter and receiver, are performed by discrete transistor circuits.

My son’s radio-controlled car uses a carrier frequency of 27 MHz. This frequency is known as an Industrial, Scientific, and Medical (ISM) band. There are many ISM bands recognized around the world, and contrary to their name, they are the RF bands used by most consumer products. Probably the most crowded ISM band for consumer applications is 2.4 GHz, which is used by cordless phones, Bluetooth, WiFi, and even your microwave. (For more information about ISM bands see my blog: How to select the frequency of a wireless product.)

Transmitter design
Let’s start by looking at the transmitter circuit located in the hand-held controller. The block diagram for the TX-2B is shown below in Figure 1. The TX-2B handles the encoding for five different functions (forward, back, left, right, and turbo). When a button is pressed, a digital code representing one of these functions is serially output on pin 8. The frequency of this data signal is about 1 kHz.

Figure 1

Internal block diagram for the TX-2B transmit encoder chip

Internal block diagram for the TX-2B transmit encoder chip

Now let’s take a look at the schematic for the full transmitter circuit in Figure 2 (obtained from the TX-2B datasheet).

Figure 2

Schematic for transmitter circuit

Schematic for transmitter circuit

A simple 3V zener regulator is created using D1 and R5 to power the TX-2B. Rosc sets the internal oscillator frequency of the TX-2B to 128 kHz. The 27 MHz carrier signal is generated by the oscillator circuit formed with X1, Q1, and L1. R1 sets the bias current for Q1, while R2 provides current limit protection. The encoded data signal on pin 8 of the TX-2B is then coupled with the carrier signal through C1. The coupled signal is shown below in Figure 3.

Figure 3

Data signal coupled with 27 MHz signal

Data signal coupled with 27 MHz signal

This signal is then fed into the AC gain stage formed by Q2 and L2. Because of the large magnitude of the data signal this gain stage is only active when the data line is high. When the data line is high the 27 MHz carrier signal gets amplified, but when the data line is low the Q2 gain stage is turned off. The resulting waveform on the collector of Q2 is simply the amplified carrier signal being turned on/off by the data signal.

This method of radio communication is called continuous wave (CW) radio. CW is the simplest type of radio transmission. In fact, it’s the method of radio communication used by telegraph machines to transmit Morse code. The continuous wave signal on the collector of Q2 is shown below in Figure 4.

Figure 4

Continuous-wave signal output to antenna

Continuous-wave signal output to antenna

The CW signal is AC coupled through C2 to remove any remaining DC component. A pi-network consisting of L3, C3, and C4, along with L4, is used for impedance matching with the antenna. Proper impedance matching is critical for optimizing the efficiency of the antenna.

Receiver design
The receiver circuit located in the car is a bit more complicated than the transmitter circuit. This is partly because it also includes H-bridges for driving the two motors (propulsion and steering). Figure 5 below shows the block diagram for the RX-2B.

Figure 5

Continuous-wave signal output from amplifier to the antenna

Continuous-wave signal output from amplifier to the antenna

The encoded 1 kHz data signal is input to pin 3, then internally amplified and decoded. Once the corresponding function has been determined from the decoded signal, the appropriate output pin is enabled for either forward, backward, right, left, or turbo. The full schematic for the receiver circuit (from the RX-2B datasheet) is shown below in Figure 6.

Figure 6

Schematic for receiver circuit with H-bridge motor drivers

Schematic for receiver circuit with H-bridge motor drivers

The receiver is the circuit built around Q1. This type of receiver is known as a regenerative receiver because it uses positive feedback. A tuned LC circuit consisting of L2 and C3 provides positive feedback but only at the tuned frequency (27 MHz). So this means that only the intended signal gets amplified by the positive feedback. One downside of this type of receiver is that L2 must be custom coiled in order to accurately tune the receiver.

The output signal from the receiver circuit goes to pin 14 on the RX-2B. This signal is now filtered to remove the carrier and ran through two internal inverters. By the time the signal makes it to the RX-2B signal input pin (pin 3) it has been filtered and cleaned up enough that only the 1 kHz data signal remains. As with the TX-2B, a 3V zener regulator is used to power the RX-2B. Rosc again sets the internal oscillator frequency to 128 kHz.

Two standard H-bridge circuits are used for the propulsion motor and the steering motor. The H-bridge allows the direction of the motor to be controlled by switching the direction of current flow through the bridge and motor. The circuit shown in the RX-2B datasheet had several errors that have been corrected in the schematic shown above. The turbo function increases the current through the propulsion motor (via Q3) but only when the forward direction is selected.

Antenna design
Using a lower carrier frequency, like 27 MHz, has several advantages. It allows slower, lower-cost devices to be used for the RF sections. Secondly, the design isn’t as sensitive to PCB layout effects. Finally, for the same output power a lower frequency carrier will offer a larger range compared to higher frequencies. The big disadvantage is that lower carrier frequencies require larger antennas.

Radio-controlled cars use a monopole antenna (versus a dipole antenna — like rabbit ears). A monopole antenna mimics a dipole antenna by using the reflective properties of a ground plane, in this case Earth itself. For peak efficiency the antenna needs to be designed to resonate at the desired carrier frequency. To achieve this the antenna needs to be 1/4 the length of the wavelength of the radio waves being communicated. The wavelength can be calculated using:

    Wavelength = Speed of light / Frequency

The speed of light in a vacuum is 300 x 106 m/s, but it is about 5% slower in a metal. So assuming a 1/4 wavelength antenna, and a 27 MHz carrier, the antenna length should be:

    Antenna length = (0.95 x 0.25 x 300 x 106 ) / (27 x 106 ) = 2.6 meters

However, 2.6 meters is an unpractically long antenna for many applications, like a small toy car. Either a coiled antenna must be used to get the required length, or a loading coil can be used to make the antenna resonate at a shorter length. In the case of my son’s car, neither of these techniques is used. Instead, a telescoping antenna only about 15 inches long is used. The poor efficiency from using too short of an antenna drastically reduces the range. But for a short-range toy the reduced range is acceptable. The cost savings of using a low frequency outweighs the reduced range for some low-cost products.

I must say it feels good to finally have accomplished my childhood goal of understanding the details of how a radio-controlled toy works. I know many engineers are born with a passion for figuring out how things work, so please share with readers what toys you tore apart as a child by commenting below.

60 comments on “Design for a Radio-Controlled Car

  1. nasimson
    December 30, 2014

    Thank you John for de-mystifying a chilhood mystery for me. Now I can say that unserstand it to some extent. Your blog you linked to about selecting the frequency of a wireless product is very insightful as it covers the global use of frequency.

  2. amrutah
    December 30, 2014

    John,

       This is a very nice and descriptive blog post.  The design details are truly awesome to understand the basic of operation.

       Why is this not a chip solution instead of the board design, what is causing the limitation? Inductors or Bipolars?

  3. teelengineering
    December 30, 2014

    Thanks for the positive comments!

    I believe cost and simplicity were the reasons for not using a chip solution.  The discrete devices they used are extremely cheap.  These RF circuits have been around for many decades so they are well tested and well known.  Also there are very few chip solutions I've seen available that work down to 27 MHz.  A chip solution would also probably need a microcontroller adding additional cost and complexity.  Finally, more advanced (ie expensive) radio-controlled cars may use more of a chip solution, and this was a very cheap toy for my 2 y/o son.

  4. samicksha
    December 30, 2014

    Good One, but this blog made me curious to ask if we can have circuit that can carry analog signal for proportional control.

  5. teelengineering
    December 30, 2014

    Yes, you could transmit a proportional signal using this same method of communication (continous-wave).  You'd need a different encoder/decoder chip since this one is only designed for 5 on/off functions.  You'd of course need an ADC on the transmitter and a DAC on the receiver.  You'd also need some modifications to the H-bridges since these are currently designed only for on/off control.  So considerably more complex, but possible.

  6. Sachin
    December 31, 2014

    @John, thanks a lot for the post. Very informative. I am curious to know why lower carrier frequency of 27MHz was chosen ? Do we have the flexibility to vary this ?

  7. Sachin
    December 31, 2014

    Why is this not a chip solution instead of the board design, what is causing the limitation?

    @amrutah, I dont think its a good idea to opt for chip solution if the number of quantity we want to manufacture is huge in number. If the number of quantity that we want to manufacture is small then its always better to implement it in board rather than chip.

  8. teelengineering
    December 31, 2014

    27 MHz allowed the use of slower devices which are cheaper.  40 MHz is another common ISM band available worldwide that could be used, but the next ISM band after that is 315 MHz which would probably require more expensive devices and a better PCB layout for RF.  Also the same transmission distance would take more power (less battery life) at higher frequencies.  Most of the ISM bands, including 315 MHz, 433 MHz, 915 MHz are not universally available around the globe like 27 MHz.  Not until you reach 2.4 GHz do you get another ISM band that is available worldwide.

  9. Sachin
    December 31, 2014

    @teelengineering, thanks a lot for the detailed explanation. That solves all the doubts i had.

  10. Davidled
    January 1, 2015

    If the frequency is changed from 27 MHz to a different value, I guess that transmitter XTAL might be changed and antenna could be redesigned based on formulation that you commented. Plus, antennas location and PCB board related to it could impact performance.

  11. goafrit2
    January 1, 2015

    >> our blog you linked to about selecting the frequency of a wireless product is very insightful as it covers the global use of frequency.

    Grear content. The only downside is the use of BJT in the device. I wish we can do all with CMOS which many of us are very experienced and knowledgeable on how to work with. Too bad, I did not pay attention to BJT in college thinking it was a by-gone.

  12. goafrit2
    January 1, 2015

    >> Why is this not a chip solution instead of the board design, what is causing the limitation? Inductors or Bipolars?

    Complexity and difficulty. At this frequency, ASIC may be harder.

  13. goafrit2
    January 1, 2015

    >> Finally, more advanced (ie expensive) radio-controlled cars may use more of a chip solution, and this was a very cheap toy for my 2 y/o son.

    Possible to have the Gerber files or Protel shared. I am interested in making this board.

  14. teelengineering
    January 1, 2015

    Sorry not that I know of.  I didn't design the circuit so I don't have gerbers, etc. 

  15. teelengineering
    January 1, 2015

    BJT's still have many uses and advantages in some applications.  So I don't recommend ignoring BJT's.  They are slightly more difficult to understand than MOS but still very useful.

  16. Navelpluis
    January 2, 2015

    Thanks John for posting this thorough article. I always knew that there was a PCM based chipset inside these tools, but now we all know exactly how it works. Full AM modulation with a not-perfect steering control. I see our gift bounce against the walls time over time 😉

     

  17. Victor Lorenzo
    January 2, 2015

    @goafrit2 >> “Possible to have the Gerber files or Protel shared. I am interested in making this board.

    I was also interested on this circuit a few years ago for controlling some sort of toys for my son. My idea was salvaging some old cars we have laying around.

    What I found with the circuit was it has a very high power consumption, it dryes the batteries too fast.

    The circuit is perhaps too complex for simple applications. It is easy to obtain much better results integrating other readily available sub-GHz communication interfaces and one crystalless AVR or PIC microcontroller.

    I cracked open one remote control toy car for you to see the circuit. Here is a picture:

  18. Victor Lorenzo
    January 2, 2015

    @teelengineering and @samicksha,

    Standard radio transmitter/receivers for remote servo control applications (e.g. R/C planes) use multichannel PWM signals for sending the equivalent to a proportional analog control signal. Pulse width ranges from 1ms (-90º deflection) to 2ms (+90º deflection).

    Many R/C transmitters have a serial/parallel or analog input interface for master/slave (instructor/trainee) operation which are well suited for PC (or MCU) control.

    Multi-channel receivers deal with all the reception/decoding tasks and provide independent PWM channel outputs.

    I've used this same schemma for controlling several standard (Hitech) R/C servos from an FPGA running NIOS-II. It is easy to implement and fun to play with.

  19. varunopen7
    January 2, 2015

    very nice design

  20. Davidled
    January 2, 2015

    I guess that either FPGA or 8 bit microcontroller might be used in the board, including a radio based car control program.

  21. amrutah
    January 2, 2015

    @SachinEE: I thought same chip can be used in multiple radio-control gaming applications, which is essentially a large market in developed countries.  As earlier said in one of the threads, it is better to use the already present robust designs of OPAMPS.  There is no much scope for innovation which defeats the purpose of new design.

  22. amrutah
    January 2, 2015

    At this frequency, ASIC may be harder.

    @goafrit: Wish You a Happy New Year.

    I don't understand this, please help me.  There are chips that operate at 100 GHz range, why does a 27MHz operating design be difficult?

  23. goafrit2
    January 2, 2015

    Sure, no one is saying that we can do without BJT. It is still the choice for RF designs and other HF projects. The challenge though is that many will simply avoid it if CMOS can be a good substitute

  24. goafrit2
    January 2, 2015

    >> The circuit is perhaps too complex for simple applications. It is easy to obtain much better results integrating other readily available sub-GHz communication interfaces and one crystalless AVR or PIC microcontroller.

    Yes, I think so despite the praise by the community. It is going to cost excess of $90 to get that in production looking at the different parts. But China sells RC toys with controllers for sub-$30. You are right, we may need a new design paradigm that has more integrations

  25. goafrit2
    January 2, 2015

    >> I guess that either FPGA or 8 bit microcontroller might be used in the board, including a radio based car control program.

    If you use FPGA in a toy project, you may not likely find a buyer because of the cost!

  26. goafrit2
    January 2, 2015

    >>I don't understand this, please help me. There are chips that operate at 100 GHz range, why does a 27MHz operating design be difficult? It is contextual.

    If you open many RC toys from China where they get the cost to less than $30, they use ASIC to get better cost model. Of course you can use a board but it may become exotic to get a mom to pay for it. The point is at this frequency, you have no problem to use ASIC just as you can use a board. The goal is cost-efficiency.

  27. Victor Lorenzo
    January 3, 2015

    @goafrit2 >> “It is going to cost excess of $90 to get that in production looking at the different parts

    Transistors: €0,03/unit (MOQ=5K), Resistors: €0,011/unit (MOQ=50), Capacitors: €0,033/unit (MOQ=50), PCB: €0,40 (MOQ=1K), RX2C IC: $18,00/20 units + $1,05 shipping, Assembly: €2,50/unit (MOQ=500)

    In quantities of 1K units it is possible to reduce cost to something under $5,00 / receiver board.

    I'm not taking into account tooling cost for PCB manufacturing and assembly.

  28. Myled
    January 5, 2015

    “I recently bought my son his first radio-controlled car. Playing with it reminded me how as a young child I loved to get radio-controlled toys so I could tear them open to figure out how they worked. The magic of the electronics is what fascinated me. It was this early curiosity that helped drive me toward a career in electronics engineering.”

    John, I think toys; especially electronic toys can create some impact in kids for formulating their passion.  Some kids looks into their electronic parts and at the same some other kids may be interested in their mechanical designs. Only thing is parents have to understand their passion and direct them to such routes.

  29. Myled
    January 5, 2015

    “If you open many RC toys from China where they get the cost to less than $30, they use ASIC to get better cost model. Of course you can use a board but it may become exotic to get a mom to pay for it. The point is at this frequency, you have no problem to use ASIC just as you can use a board. The goal is cost-efficiency.”

    Goafrit, you are right about the cost factor, especially with Chinese made toys. But I heard that Chinese toys are not following any RoHS standards and it can harm kid's brain and health.

  30. fasmicro
    January 6, 2015

    >> In quantities of 1K units it is possible to reduce cost to something under $5,00 / receiver board.

    That is a lot of margins – no wonder some Western phone companies are working harder to ban Xiaomi (Chinese phone maker)  from coming into U.S. /Europe with their phones. It seems some of these electronics products enjoy huge margins.

     

  31. fasmicro
    January 6, 2015

    >> John, I think toys; especially electronic toys can create some impact in kids for formulating their passion. 

    Largely, that is the main purpose of toys. Without the impacts or emotion, you cannot engage the kids or entertain them. My boy loves mobile toys as that amazes him. I had hoped to also get a drone. The problem though is getting into trouble  as I live in an urban area. 

  32. fasmicro
    January 6, 2015

    >> But I heard that Chinese toys are not following any RoHS standards and it can harm kid's brain and health.

    That is not an issue. I will focus on the American companies importing them. So, if I buy it in Walmart and it turns out the toy did not follow RoHS standards, I will say it is Walmart that is at fault. Some of the Chinese factories exist solely for their American customers. So, when you get 80% of your revenue from one company, anything you do cannot be decoupled from that firm

  33. Victor Lorenzo
    January 6, 2015

    @fasmicro >> “That is a lot of margins

    Yes, but should also take into account molding, machining, other mechanical parts, packaging, handling, distribution, advertising….

  34. goafrit2
    January 6, 2015

    Yes, but should also take into account molding, machining, other mechanical parts, packaging, handling, distribution, advertising….

    Electronics could look like a really appealing idea but when you get into the details, you will notice that may not be. The fact is testing cost could drop that margin significantly.

  35. nasimson
    January 6, 2015

    @fasmicro:

    > no wonder some Western phone companies are working harder to ban Xiaomi
    > (Chinese phone maker)  from coming into U.S. /Europe with their phones.

    Which western phone companies are these? Apple? Otherwise all significant phone companies are Chinese/Korean/Taiwanese anyways: Samsung, Huawei, HTC, ..

  36. nasimson
    January 6, 2015

    @MyAnalog:

    > But I heard that Chinese toys are not following any RoHS standards
    > and it can harm kid's brain and health.

    Thats alarming. Can you share the reference that contains details of this non-compliance. My kids are playing wth Chinese toys all the time. And I guess thats the case with most of us.

  37. nasimson
    January 6, 2015

    @ MyAnalog:

    > especially electronic toys can create some impact in kids for
    > formulating their passion.  Some kids looks into their electronic
    > parts and at the same some other kids may be interested in their
    > mechanical designs. 

    Are there any electronics kits that teach children basics of electronics in a simple manner. LEGO should have been making some for primary-level kids as they also make robotics for college kids.

  38. nasimson
    January 6, 2015

    @fasmicro:

    > I will say it is Walmart that is at fault. Some of the Chinese factories
    > exist solely for their American customers. So, when you get 80% of
    > your revenue from one company, anything you do cannot be decoupled
    > from that firm

    Thats a good point. Walmart and ToysRUs are equally responsible for the production and supply chain practices of  their partner.

  39. Victor Lorenzo
    January 7, 2015

    @nasimson >> “LEGO should have been making some for primary-level kids as they also make robotics for college kids

    LEGO has sets focused on different kid ages. The Technic (http://www.lego.com/es-es/technic/products) and Creator series include power functions (motor, IR remote control, etc.) that you can use to create amazing things.

    My son loves LEGO, in fact I love it too.

    LEGO has one drawback, it is too expensive for most people.

    Mindstorms robots (http://www.lego.com/es-es/mindstorms) are great for making even more amazing things, but at 400€ the EV3 is also out of reach for most people.

    Other toy manufacturers like fischerTechnik (http://www.fischertechnik.de/en/Home.aspx) have lots of sets for robotics.

  40. Victor Lorenzo
    January 7, 2015

    @nasimson >> “Can you share the reference that contains details of this non-compliance

    I have seen several references to this non-compliance issues from several companies for the last 10/12 years in Spain, mostly because of paintings and safety (too small removable pieces) issues.

    Take a look a this press note, in spanish, from a mexican news paper (http://www.cronica.com.mx/notas/2007/317414.html). It can give you some clues for investigating a little bit on the subject.

  41. nasimson
    January 7, 2015

    Thanks for sharing the link Victor. Its in Spanish that I dont know. Will try Google Translate though.

  42. nasimson
    January 8, 2015

    Thanks for the links Victor. I've got some good gift ideas for my kids. Exposure to Robotics and electronics at this early age result in engineering and circuit design passions in later ages.

  43. Myled
    January 8, 2015

    “Largely, that is the main purpose of toys. Without the impacts or emotion, you cannot engage the kids or entertain them. My boy loves mobile toys as that amazes him. I had hoped to also get a drone. The problem though is getting into trouble  as I live in an urban area.”

    Fasmicro, I cannot agree with your message “that's the purpose of toys”. We are giving toys only for engaging with some activity and hence kids won't disturb parents. I know many instance kids loosing interest in many toys with a weeks or couple of days.

  44. Myled
    January 8, 2015

    “That is not an issue. I will focus on the American companies importing them. So, if I buy it in Walmart and it turns out the toy did not follow RoHS standards, I will say it is Walmart that is at fault. Some of the Chinese factories exist solely for their American customers. So, when you get 80% of your revenue from one company, anything you do cannot be decoupled from that firm”

    Fasmicro, I mentioned in general about the health hazard issues with such toys. Not intentional meant for any company or country or retailer. Retailers are only a part of the chain and they are interested in selling any products from any companies; especially when they are offering better margin/commission.

  45. Myled
    January 8, 2015

    “Thats alarming. Can you share the reference that contains details of this non-compliance. My kids are playing wth Chinese toys all the time. And I guess thats the case with most of us.”

    Nasimson, these are articles and study reports published through journals and print medias. I haven't any thing for a ready references; but read a lot about such things.

  46. Myled
    January 8, 2015

    “Are there any electronics kits that teach children basics of electronics in a simple manner. LEGO should have been making some for primary-level kids as they also make robotics for college kids.”

    Nasimson, yes there are basic building block available with Amazon and eBay. These Kits can contain, breadboard, insulated wires, assembly diagram, components in simpler form, bells or buzzers etc.  I feel that those things are helpful for kids above 7 years. 

  47. samicksha
    January 13, 2015

      I admit i have not been a good fan of RC cars, i guess Kv number tells how many RPM the motor will turn per volt, assuming no load and maximum efficiency. However, the ability of the system to put out power is dependent on the quality of the batteries used, wires and connectors supplying power.

  48. Myled
    January 14, 2015

    “I admit i have not been a good fan of RC cars, i guess Kv number tells how many RPM the motor will turn per volt, assuming no load and maximum efficiency. However, the ability of the system to put out power is dependent on the quality of the batteries used, wires and connectors supplying power.”

    Samiksha, thanks for this clarification. Yes, battery power is a major factor in pulling the engine against the torque.  In such driving test condition, road condition and application of brake also matters.

  49. amrutah
    January 20, 2015

    “we may need a new design paradigm that has more integrations…”

    @goafrit: I agree, we need more integration.  But that also means we will add new technologies, features and that might boomerang by the way of increasing the costs.

  50. amrutah
    January 20, 2015

    This is nice discussion and thanks for the comments.  Many things to think off and apply.

  51. ue2014
    January 29, 2015

    >>>>>>> John, I think toys; especially electronic toys can create some impact in kids for formulating their passion. >>>>  Only thing is parents have to understand their passion and direct them to such routes. >>>>>>>

    Totally agree with you. Toys we provide to them could trigger a stimulation on them towards electronics. But its equally important that parents identify effectively what the kids are really interested in before they direct them in such routes. I have a friend of mine who wish his son to be in the same field he is just beause he (my friend) enjoys that feild, which might not be the case for the kid.

  52. ue2014
    January 29, 2015

    >>>>>>>>>>>>>  I know many instance kids loosing interest in many toys with a weeks or couple of days.>>>>>>>>>>

    Agree with you. But there are cases where when a toy is provided for a kid, later you find he has seperated it to parts and really interested in finding what happens inside and how this thing really works. 

    Such senarios gives parents an opportunity to identify what their kid is really interested in. On the other hand, from the kind of toys the kid request to have also could give you a sign too. 

  53. nasimson
    January 30, 2015

    > I have a friend of mine who wish his son to be in the same
    > field he is just beause he (my friend) enjoys that feild, which
    > might not be the case for the kid.

    @ue2014: Doctor's son to be a doctor. Engineer's son to be an Engineer. Wrong paradigm. Humanity is thankful that Mozart's, Einstein's and Gandhi's parents didnt force their own career on their kids.

  54. ue2014
    January 30, 2015

    Good one. Luckily my father was not a one of them. If so, I would have been a military officer by now. People should learn to understand value of each profession. Not only doctor's, engineering are accepted as excellent professions with good identity in society.

  55. goafrit2
    February 2, 2015

    I agree, we need more integration.  But that also means we will add new technologies, features and that might boomerang by the way of increasing the costs.

    That is the only way that scaling brings better returns. Integration is at the heart of the industry and we continue to reap the benefits of the works of Jack Kilby and Roberty Noyce on this.

  56. goafrit2
    February 2, 2015

    I have a friend of mine who wish his son to be in the same field he is just beause he (my friend) enjoys that feild, which might not be the case for the kid.

    The interesting thing is that most kids will follow their parents into a field as they seem them as role models. When you have many law books at home, do not expect the kids to be overly interested in medicine. As you said, you need to give them space to open their imaginations.

  57. goafrit2
    February 2, 2015

    Humanity is thankful that Mozart's, Einstein's and Gandhi's parents didnt force their own career on their kids.

    I agree with you especially in a time when even working for another person is becoming old fashion. People want to think and build startups and companies.

  58. falcon.m
    March 7, 2015

    Sir thank you very much for explaining it…i am going to make a RC Car in my semester project..its my first project and i am very excited..can you kindly guide me about designing its circuit on proteus and i have a couple of questions to ask you…

    in the circuit diagrams there are only two motors attached with the receiver,please kindly tell me what kind of motors are they?…and can we attach two motors for the rear wheels, each motor for one wheel?if so then what would be the changes made in the circuit???????????????????????

    waiting for your reply 

    thanks

  59. Vicky_nk@hotmail.co.uk
    June 6, 2015

    Hi,

     

    It will be hard and pain for you to get these circuit work as a newbie.

    If you need the simple one please get these module: QAM-TX2 and QAM-RX2 module from  WWW.QUASARUK.CO.UK and the encoder and decoder RF600E and RF600D.

    for the motor you can use any type.  There are million of these motor in the market or you can get them from old used car.

     

    I tried these module and worked perfectly on bread board. But I didn't use motor as load instead I just hooked some LED to show me the status of my RX output when a button connected to my RX circuit was pressed.

     

    I think my information will help you to enjoy your time.

  60. amplificatorul
    September 1, 2020

    how can i see the other “59 comments”?

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