Support in learning the art of electronics

[rstofer]

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

[rstofer]

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.

[orolo]

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.

[akos_nemeth]

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

[Mule]

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,

[rstofer]

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.

[Mule]

Ahh yes all so obvious now. Thank you very much.

[coolyota]

Hello, I am attempting to do the lab 1L.3 on page 27 but very confused of what to do. It says we are making a voltmeter but doesn't have instructions or parts I need. What am I supposed to do for this section of LAoE?

[rstofer]

1) you need a meter - say 0-1 mA full scale
2) you need to calculate the internal resistance by building a voltage divider with, say, a 1k divider resistor and a variable voltage source 0-2V (or 10k 0-12V).  Anything that is adjustable and can provide 1 mA while including the unknown internal resistor
3) set your variable power source to just move the needle to full scale and measure the output of the voltage source
4) calculate the internal resistance from the voltage divider equations by first calculating the total resistance from your measured voltage divided by 1 mA.  Then subtract off the divider resistor and what you have left is the internal resistance
5) now that you know the internal resistance, you can compute voltage divider resistors for various ranges like 0-1V, 0-10V, 0-100V and so on.

[rstofer]

If you don't have a meter, you can use a DMM on some low current measurement range.  I can set my Aneng 8008 (cheap meter) for a range of 0-9.999 mA so I can know exactly where 1.000 mA comes up.

Personally, I would use the DMM even though the instructions recommend a bare meter.  That's fine, if you happen to have one.  Not so fine if you have to go buy one.

If you buy a quality meter, like a Simpson, you can go to their catalog and find out what the internal resistance is supposed to  be.  Kind of a cross-check on the calculation.  If you buy a meter from Yuan-Hung-Low, you're on your own.

Page 5 shows a 0-1 mA meter as having 43 Ohms of internal resistance.  If I want to measure 0-100V then I need to figure a total resistance of 100 V / 1 mA = 100,000 Ohms.  My meter accounts for 43 Ohms so I need a 99.957K resistor.  99.95 seems to be available at DigiKey  Part number    Y145399K9500A9L-ND 0.05%

Available but not in stock and it looks like you have to buy 2500 at a time.  I would use 100k and call it good enough.

https://www.simpsonelectric.com/images/File/datasheets/widevue_datasheet.pdf

[coolyota]

1) you need a meter - say 0-1 mA full scale
2) you need to calculate the internal resistance by building a voltage divider with, say, a 1k divider resistor and a variable voltage source 0-2V (or 10k 0-12V).  Anything that is adjustable and can provide 1 mA while including the unknown internal resistor
3) set your variable power source to just move the needle to full scale and measure the output of the voltage source
4) calculate the internal resistance from the voltage divider equations by first calculating the total resistance from your measured voltage divided by 1 mA.  Then subtract off the divider resistor and what you have left is the internal resistance
5) now that you know the internal resistance, you can compute voltage divider resistors for various ranges like 0-1V, 0-10V, 0-100V and so on.

Correct me if I understood it.

Adjust power source until the DVM reads 1mA on the display. Then determine the R_T by V_in / I.
Internal resistance = R_T - R (in this case I picked a 10k Ohms Resistor).

[rstofer]

1) you need a meter - say 0-1 mA full scale
2) you need to calculate the internal resistance by building a voltage divider with, say, a 1k divider resistor and a variable voltage source 0-2V (or 10k 0-12V).  Anything that is adjustable and can provide 1 mA while including the unknown internal resistor
3) set your variable power source to just move the needle to full scale and measure the output of the voltage source
4) calculate the internal resistance from the voltage divider equations by first calculating the total resistance from your measured voltage divided by 1 mA.  Then subtract off the divider resistor and what you have left is the internal resistance
5) now that you know the internal resistance, you can compute voltage divider resistors for various ranges like 0-1V, 0-10V, 0-100V and so on.

Correct me if I understood it.

Adjust power source until the DVM reads 1mA on the display. Then determine the R_T by V_in / I.
Internal resistance = R_T - R (in this case I picked a 10k Ohms Resistor).

Yup!  That concept is all the experiment is supposed to show.  As additional information, you can review the schematics of the popular Simpson 260 VOM starting with the original version manufactured in 1940.  This is some serious history!  This schematic doesn't show the switch but it is pretty easy to step through the voltage divider chain for the various voltage ranges.

http://www.simpson260.com/downloads/downloads.htm

Look specifically at this version and you can see the protection diodes that are discussed in a note to the instructor in the lab manual.

http://www.simpson260.com/downloads/simpson_260-7_and_7m_schematic.pdf

There are applications where VOMs are still the preferred tool.  Think about the starter in a car and the internal condition of the battery.  Suppose the battery has developed a relatively high internal resistance.  When the starter cranks the voltage drops.  This is hard to see on a DMM but it's very easy on a VOM.  The meter will read 12V, like normal, and you could swear the battery is just fine.  Hit the starter while watching the needle and everything will be explained.

[rstofer]

There is one other consideration:  The voltage source has an internal resistance and we didn't account for it.  Usually, this will be a small number of Ohms but it is not zero.  It might be essentially zero when compared to a 10k divider.

The higher the applied voltage and the higher the dropping resistor, the less important this internal resistance will be.  You can calculate the voltage source internal resistance by first measuring the open circuit voltage and then measuring the voltage with a known (and low valued) resistor.  This is an application of Thevenin's Theorem, also a topic for this experiment.

Maximum power transfer (P = I * E) will occur when the load resistor is exactly equal to the internal resistance of the source.  Also a result of Thevenin's Theorem.  And it might smoke the battery, do be careful!

[khatus]

I have the book The art of electronics (3rd edition) . But I don't think it's a good book for theoretical analysis.it's more related to practical

[rstofer]

I think 'practical' was the authors' intent.  They tend to not use deeper math and spend more time talking about actual circuits.  I have the book but I haven't done anything with it.

[rhb]

I was also planning on doing the same thing, but with the previous version of the books which I had to purchase while in school. However, I just learned about this new version today. For those that have experienced both the second and third edition, what are your opinions on whether or not it's worth it to pick up the most recent version?

I bought and read the 2nd ed years ago.  I was on the verge of writing a letter to the authors begging them to update the book when the 3rd came out.  It's well worth the money.  But I'd keep the 2nd as you might well find that some useful information is mentioned there but not in the 3rd.

A lot of the parts mentioned in AoE 2 are *very* hard to find.  And there are much better options for a lot of things.  I'd like to suggest "Electronic Principles" by Malvino and Bates.  Don't get the current edition as it is insanely expensive.  AoE is pretty advanced for a novice.   The original target audience was physics students embarking on a PhD in experimental physics.  So H&H wanted the book to focus on what the mathematics *didn't* tell you.  But they really do presume you know all the math already.

I worked through the 2nd ed of "Electronic Principles".  Unlike many authors, Malvino went to the trouble to actually construct *every* circuit published to make sure there were no typos.

FWIW It is my understanding that the the AoE lab manuals are riddled with typos.

[rhb]

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

That circuit provides gain at audio.  A common way to get gain at RF in a simple radio is to attach the gate of a JFET to the antenna. 

http://www.techlib.com/electronics/antennas.html

This is what you want:

[

You can reduce it to a single transistor by breaking the circuit at the base divider of the 3904.  But the circuit shown is worth building in a small box for future use as a bench tool.  It's *very* basic, but a lot of times that is all you need.  Use a pair of  female  BNCs and a barrel connector and add an LED to indicate that it has power.  Leave off the switch unless you choose to use a battery.  But do yourself a favor.  Put labels on the box.  I've found a bunch of such things I built 30+ years ago and which I now have no idea what they are for.

You should analyze the circuit to determine bias points, currents, etc.

FWIW I'm 65 and recently allowed myself the indulgence of buying over $10K of T&M gear.  So what have I built lately?

A continuity tester powered by a AAA cell in a small box with a 1.5-3 V buzzer from allelectronics.com and two banana jacks so I can safely trace 1.8 V logic level circuits.  My HP 34401As supply ~7 V for the continuity test.  That's a recipe for causing serious damage trying to trace modern logic.

The next project was a level shifter in a box with 8 banana jacks using this board:

https://www.allelectronics.com/item/llc-46/logic-level-converter-bi-directional/1.html

A pair for each logic level and then the 4 logic signals. $3 of electronics in $10 of box.

Let's suppose you have a piece of test gear with a CPU and ROM and it's not working because one of the ROM address lines is a bit flakey and ROM images are not available.  So you *really* need to read the flakey ROM.  By connecting the problem address line Vcc to a bench supply you can bump up the voltage of that one address line a few percent above the normal logic level and see if you can dump the ROM with a logic analyzer.

I'm doing another one with DB-9 connectors for RS-232 conversions.  That will require special cables, so it will all eventually go into a small storage case with instructions on using it.  I was rather dismayed to go though a box of stuff I'd built 30 years ago and realize I had no clue what they did.

I've designed more complex stuff, but I needed these gadgets.  The 1.5 V buzzer won't trace into a BGA, so I'm contemplating a pulsed LF signal and a detector version to handle that.  A test bench version of the signal tracers they sell for sorting out telephone wiring.

Ask good questions and you will get good answers. Ask poorly thought out questions and you will get answers of equal quality.  There are some *really* smart people who hang out here because they enjoy talking about this stuff.

[rstofer]

There are some much simpler radios, some as simple as a single diode and a 30' antenna.
https://electronics.howstuffworks.com/radio9.htm

I couldn't find the lab in my 3rd edition - I must have just  been looking in the wrong chapter.

[rhb]

The lab manual is a separate book.

The OP's question was about adding an RF (high frequency) amplifier, not an AF amplifier.  so the prior answer was going in the wrong direction.

As I have suitable parts on hand, I think I'll build the circuit I posted for my own use.  It's *very* basic, but for a general purpose RF amplifier for LF to VHF it's certainly satisfactory if carefully built Manhattan style.

[rstofer]

Well, I don't think so.  We have some voltage drop across the ballast resistor based on collector current, we have V_f of the LED and that's going to be a couple of volts (usually), we have V_ceSat for the transistor (on the order of 0.2V) and, once this is all worked out, we can figure I_c

Let's take some 'pretend' numbers like Vf = 2.2V.  Then 3.3V - 2.2V - 0.2V - (330 * I) = 0

330 * I = 0.9V so I = 0.9 / 330 = 2.7 mA - probably not going to be enough to light up the LED - check the datasheet.

Looking at the base,we have 0.7V_beSat so we're thinking about 2.6V drop across 10k or 0.26 mA so we need a minimum Beta of 10.4.  I_c / I_b

Now, we need to know the real numbers:  What is V_f of the LED?  What is V_beSat of the transistor?  What is V_ceSat of the transistor?

Anyway, that's the way I would approach it.  I have no idea what the books expects.