Author Topic: Support in learning the art of electronics  (Read 9477 times)

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Offline Chai

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Re: Support in learning the art of electronics
« Reply #25 on: April 22, 2016, 03:49:12 am »
Was anyone able to find out more information about the mystery boxes used in 1L.5 page 30? The footnote says to see their website for details but I couldn't find something. I guess one would just be  a resistor? and the other might contain a resistor in series with diode?  :-//
 

Offline MrSlack

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Re: Support in learning the art of electronics
« Reply #26 on: April 22, 2016, 03:54:06 am »
They are an RC combination I understand, usually provided by the lab staff. Actual values and configurations are not discussed.
 

Offline Chai

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Re: Support in learning the art of electronics
« Reply #27 on: April 22, 2016, 05:05:24 am »
They are an RC combination I understand, usually provided by the lab staff. Actual values and configurations are not discussed.

Oh, OK. Maybe I'll pick out a few RC combos found in next section and test those.  :-/O

Also, what to do about the need for a 6.3 VAC transformer in 2L and beyond? What's the safest way for a beginner hobbyist to hook this guy up? I guess I could just use the 2ch function generator I ordered to emulate this instead of dealing with mains (?).
 

Offline rstofer

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Re: Support in learning the art of electronics
« Reply #28 on: April 22, 2016, 05:12:28 am »
They are an RC combination I understand, usually provided by the lab staff. Actual values and configurations are not discussed.

Oh, OK. Maybe I'll pick out a few RC combos found in next section and test those.  :-/O

Also, what to do about the need for a 6.3 VAC transformer in 2L and beyond? What's the safest way for a beginner hobbyist to hook this guy up? I guess I could just use the 2ch function generator I ordered to emulate this instead of dealing with mains (?).

I wouldn't do that to my function generator.  Transformers usually drive rectifiers that drive large capacitors and such.  The lowly transformer can take a lot of abuse.

Just buy a transformer, connect a power cord and be done.  There should be a switch.  You can buy any kind of switch and put it in a box.  Maybe put the transformer in the same box and just run the power cord out the back and have 2 or 3 binding posts in the front.  I assume you will be using this for a long time.
 

Offline Chai

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Re: Support in learning the art of electronics
« Reply #29 on: April 22, 2016, 05:19:46 am »
They are an RC combination I understand, usually provided by the lab staff. Actual values and configurations are not discussed.

Oh, OK. Maybe I'll pick out a few RC combos found in next section and test those.  :-/O

Also, what to do about the need for a 6.3 VAC transformer in 2L and beyond? What's the safest way for a beginner hobbyist to hook this guy up? I guess I could just use the 2ch function generator I ordered to emulate this instead of dealing with mains (?).

I wouldn't do that to my function generator.  Transformers usually drive rectifiers that drive large capacitors and such.  The lowly transformer can take a lot of abuse.

Just buy a transformer, connect a power cord and be done.  There should be a switch.  You can buy any kind of switch and put it in a box.  Maybe put the transformer in the same box and just run the power cord out the back and have 2 or 3 binding posts in the front.  I assume you will be using this for a long time.

OK. That sounds like a good idea!  :)
 

Offline MrSlack

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Re: Support in learning the art of electronics
« Reply #30 on: April 22, 2016, 06:51:17 am »
You can buy AC wall warts as well. Cheaper, ready packaged and does the job. They're useful for doing curve tracing as well. 9v one should be fine if you can't find a 6.3v one.

You will drive the transformer via your function generator later - this is completely fine to do.
 

Offline rstofer

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Re: Support in learning the art of electronics
« Reply #31 on: April 22, 2016, 07:34:12 am »
Driving the transformer from a function generator isn't a problem, true enough!  As long as things are linear, no big deal.  But hanging a bridge rectifier, filter capacitor and load on the other end of the transformer might cause the function generator a little stress.

A PC through-hole mount 120/240 : 6.3/12.6 transformer is about $5 at Digikey.
A similar chassis mounted transformer (my preference) is about $12.
Here's a chassis mount for $11 http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_102163_-1
 

Offline stoica adrian

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Re: Support in learning the art of electronics
« Reply #32 on: June 02, 2016, 11:18:03 pm »
Hi,

I have a question. A lot of parts for the lab i must  buy from mouser and digikey, the problem is that i am from Romania, Bucharest and the sheeping cost almost doubles the cost of that part and the total price is huge. The question is do i really need that parts or i can buy something similar from farnell which is more cheap and easy to buy for me?
 

Offline rstofer

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Re: Support in learning the art of electronics
« Reply #33 on: June 03, 2016, 01:53:39 am »
The important things are the value and ratings (voltage, current, etc) and don't worry if all you can find is a higher voltage (current) model.  I would substitute as much as possible.

Here is one version of the shopping lists:
http://learningtheartofelectronics.com/parts-lists/

Almost everything can be sourced a lot closer than the US.  One thing you can do to help with shipping is to order as much as possible in one shipment.

Pay attention to that 555 timer - you must make certain that you get a CMOS version, not one of the TTL versions.  Check the datasheet for the particular device.

You might want to do as the list author suggests and buy a resistor assortment and maybe even a capacitor assortment.  You will need the values eventually.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1311.R7.TR10.TRC2.A0.H1.Xresistor+assortment.TRS0&_nkw=resistor+assortment+1%2F4w&_sacat=0

http://www.ebay.com/sch/i.html?_odkw=resistor+assortment+1%2F4w&_osacat=0&_from=R40&_trksid=p2045573.m570.l1311.R4.TR9.TRC2.A0.H0.Xcapacitor+assor.TRS0&_nkw=capacitor+assortment+kit&_sacat=0

http://www.ebay.com/sch/i.html?_odkw=capacitor+assortment+kit&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR3.TRC2.A0.H0.Xtransistor+assortment.TRS0&_nkw=transistor+assortment&_sacat=0

You might check eBay for your location and see if these are available.
 
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Offline stoica adrian

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Re: Support in learning the art of electronics
« Reply #34 on: January 02, 2017, 07:19:35 am »
Hey guys, i need your help.
@ lab 4 in ''learning the art of electronics''' is a design exercise.
They say to design an AM radio receiver.
For the radio you  have to use use a long antena ( about 30 feet in the air using a long cable) or you can use a high frequency amplifier instead of the 30 foot antenna

My request is: can someone recommend a schematic to make this high frequency amplifier for this design. I had found a lot of schmatics on google,
but i don't know what to choose.

Thanks,
 

Offline orolo

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Re: Support in learning the art of electronics
« Reply #35 on: January 03, 2017, 01:32:01 am »
My request is: can someone recommend a schematic to make this high frequency amplifier for this design. I had found a lot of schmatics on google,
but i don't know what to choose.
Think about your circuit and try to form a criterion about the basic characteristic you need in your amplifier, starting with must haves (see below) without forgetting compromises (ease of construction, cost, availability, and your own strong and weak points). Most of the different circuits you saw could work for you.

At the input of the amplifier you should have a selective resonator, probably an inductor in parallel with a variable capacitor. You don't want to load the resonator, for it will lose selectivity: the amplifier must have a high input impedance. Since AM broadcast has a carrier frequency from 700kHz to 1.8MHZ (with country variations), your amplifier must have a bandwidth from 500kHz to 2MHz or so. You should also consider what voltage and power gain you are looking for: if an AM station is close enough, you might need none. At this stage, gain is not so important, just what your demodulator needs. Once you got the audio, you can easily amplify it.

I'd aim for an amplifier with high input impedance, 2MHz bandwidth, and at least unity gain. So review the circuits you got based on that. For example,

- Using an op-amp amplifier is ok if the IC has got the bandwidth (no 358 or 741, but TL072 does fine) and if you don't abuse the gain. Very high input impedance, fair bandwidth, fair power gain, low voltage gain.
- Using an emitter follower, if you bias it right, gives you high input impedance, lots of bandwidth, good power gain but no voltage gain. Coupling the input via a small capacitor will reject low frequency interference. This is a very good simple option for close stations. A jfet common source follower amplifier is very easy to bias and has lots of input impedance, but a bit less power gain.
- A common emitter amplifier is a compromise: medium input impedance, ok bandwidth, but you get voltage and power gain. You can't abuse the voltage gain, watch for the input capacitance. Probably best is an emitter follower and then a common emitter.

It is a good idea to know what kind of signals you will be amplifying. Probe the resonator with the oscilloscope, at the lowest voltage level; you should easily see the AM signal bursting there, in the tens of millivolts range.
« Last Edit: January 03, 2017, 02:39:10 am by orolo »
 

Offline akos_nemeth

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Re: Support in learning the art of electronics
« Reply #36 on: January 24, 2017, 09:10:28 am »
Hey guys, i need your help.
@ lab 4 in ''learning the art of electronics''' is a design exercise.
They say to design an AM radio receiver.
For the radio you  have to use use a long antena ( about 30 feet in the air using a long cable) or you can use a high frequency amplifier instead of the 30 foot antenna

My request is: can someone recommend a schematic to make this high frequency amplifier for this design. I had found a lot of schmatics on google,
but i don't know what to choose.

Thanks,

Hi Adrian,

I found this schematic for the short antenna problem:http://learn.mikroe.com/ebooks/radioreceivers/chapter/simple-radio-receiver-with-lm386-ic/


It uses the LM386 jellybean audio amplifier IC.
Do you have a tuning variable capacitor? They are not sold by Farnell, TME, Mouser, but I have seen in amazon.co.uk: https://www.amazon.co.uk/Spiratronics-CR3-016-Miniature-Tuning-Capacitor/dp/B0093Z0VP2/, also ebay has many tuning capacitors, but the real oldschool ones are not cheap...

Regards,
Ákos

 

Offline Mule

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Re: Support in learning the art of electronics
« Reply #37 on: July 21, 2017, 10:15:16 pm »
I need help in setting up the very first circuit in 2L. I have 2 BNC leads, a function generator and a scope.

I know this seems very basic but how can I drive my RC circuit with the function generator?

What do I need to be careful of? I don't want to go breaking anything.

Cheers,

 

Offline rstofer

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Re: Support in learning the art of electronics
« Reply #38 on: July 22, 2017, 12:21:40 am »
I need help in setting up the very first circuit in 2L. I have 2 BNC leads, a function generator and a scope.

I know this seems very basic but how can I drive my RC circuit with the function generator?

What do I need to be careful of? I don't want to go breaking anything.

Cheers,

Hook it up like they show it...

On the left, connect the signal generator input output leads - hot (usually red) to the resistor, ground to the common ground (3 connections should be shown tied together at this point in the book).

On the right, connect the scope probe to the junction of the resistor and capacitor, scope ground to the common ground.

At this stage in the learning process, I would be happier if they showed the 3 ground connections tied together.
« Last Edit: July 22, 2017, 09:54:57 am by rstofer »
 

Offline Mule

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Re: Support in learning the art of electronics
« Reply #39 on: July 27, 2017, 09:10:15 pm »
Ahh yes all so obvious now. Thank you very much.
 


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