I was wondering if making a low frequency RF circuit on a breadboard is viable.
Electronic – run 125kHz RF circuit on a breadboard
breadboardRF
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If built carefully and sensibly with shortest minimum lead lengths, short paths to power rails and proper decoupling and filtering then a breadboard can be not too much different than a PCB based supply. Good results can be expected and noise should not be vastly worse than a typical PCB based circuit.
If built as roughly as breadboard circuits often are then bad results can be expected. However, the low frequency (50 - 100 kHz MAY even save you in those cases.
Switches have a certain amount of magic in them. In some cases/locations a few pF of stray capacitance can make things go very wrong. BUT
I have successfully built numerous switchers on breadboards (plug in style).
Spec sheets say these operate at 100 kHz and 52 kHz so both are relatively "breadboard friendly".
The fixed voltage LM2575 has a slight edge in lashup-proofness as it has the critical feedback divider internally, but I'd recommend going with a variable output voltage version as being more useful and flexible and being able to teach you more. The LT part looks somewhat more capable overall.
Lower than higher frequency is liable to be more successful on a breadboard, so around 100 kHz is a good starting frequency. Old tech for most ICs. Even 1 MHz may be OK but capacitive coupling increases by 10X wrt 100 kHz. A 1 pF is 10 pF equiv. A 10 pF is 100 pF equiv. A few pF seldom hurt too much at 100 kHz.
Keep leads short. Group components together that share common heavy current paths. Bypass well. Do the best breadboard job you can. Avoid long loopy wires such as usually don't matter at all. Think ahead and plan it at least a little bit. Odds are it will work.
A trap is the feedback divider network (R1 & R2 in each case on datasheet page 1 diagram, but upper/lower swapped). Here yu have a feedback input pin and a divider from output to regulate voltage. Neither datasheet shows it, but a small capacitor across top resistor of divider (feedback ping to Vout) usually helps impulse response. A small cap from the centre point = Feedback pin to anywhere else is often a disaster. Ask me how I know :-). That MAY be most sensitive spot in many circuits.
Think about current paths. Inductor /switch/diode/filter caps (in and out), Ground and power sides.
If driving an external transistor (not relevant here) keep leads short. USe reverse zener across gate-source if using a FET.
The IC's chosen make life easy at the cost of some flexibility. For "playing" look at MC34063 - I recommend them to one and all. Old. Some defects. Cheap. capable and flexible and fun and low parts count. Built in high side current limit. Can do about ANY topology (boost, buck, buck boost, CUK, SEPIC, ... .
See figs 15, 20, 21 in datasheet for step down examples.
Fig 15 is with internal switch. Up to 0.5A out - maybe more.
Fig 20 uses NPN external but I'd use an N Channel FET.
Fig 21 uses PNP external - I'd use a P Channel FET.
I'd prefer Fig 20, with N-Channel FET.
This will do 36V + direct (40 V rated) BUT start at say 12V to 5V to play. MUCH more energy and things to go wrong at 36V in.
Ask more questions if of interest.
ADDED: 20 July (NZT)
The example ICs which have all pins in a straight line give every prospect of good results if used following the guidelines above and data sheet guidelines.
The IC can be positioned so that power rails are fed from breadboard strips only a few tenths of an inch away and decoupled with minimal lead lengths. There are few other components and these may be placed with very short leads.
However, this is such a simple circuit that use of "vectorboard"/ veroboard / ... etc copper strip board would allow a tidy and easy implementation with slightly less to go wrong.
When using plug in bread boards some component leads are so thick that they will either not fit or will permanently "set" the breadboard springs if inserted. These can be dealt with by soldering SHORT lengths of wire to them as lead extensions and plugging these into the board. Properly done and with leds trimmed the result looks OK and is liable to be effective.
Too thin wire may also have contact problems.
I have used plug in breadboards for many decades. I own dozens of them. They are a marvellous tool and are well worth using if used with due care and intelligence.
However, they can also cause unexpected problems. The tradeoffs are worthwhile overall but you must always be aware of the dangers.
Breadboard quality varies. Price is some indicator of quality but obviously some people will sell you cheap junk at whatever price they can get you to pay. But, if you can buy a given brand anywhere at much lower than average price it is liable to be suspect.
Be prepared to use them with care, take care of how you insert wires into them and be realistic in what you expect of them.
NEVER plug larger leaded components into them. One forced insertion may weaken the spring at that point forever. If you want to use larger leaded components, solder a small extension of thinner wire onto them. The venturesome could wrap many turns of wire around a component lead to remove the need to solder. This would often work well - but YMMV*, as always.
Use smooth plated wires without nicks. Do not use bar copper wire which can corrode. Do not use abrasive wires (nicked etc)
Be aware that the strips have high capacitance between adjacent rows - circuits that are adversely affected by a picoFarad or few of interstrip coupling are not good candidates.
Do not pass high currents through the breadboard. It may cause no problems now or in future. Or may.
Be aware that wires may pull out or short or conspire against you.
Components with very small diameter leads (eg some TO92 transistors) MAY make poor contact. I usually have no problems with TO92 style transistors.
Even Olin says breadboards have their place.
So they must be OK.
:-)
Your flipflop problem MAY have been caused by a floating set or reset piu - ie not a fault of the breadboard.
What frequency was the flipflop operating at?
Frequencies of a few MHz may be OK.
10 MHz maybe.
Higher than that is "adventurous".
*YMMV = Your mileage may vary ~~= "Are you feeling lucky, Punk?"
Best Answer
In my experience, yes, but you may need to take a few things into account.