My take on curve tracers for beginners - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: March 30, 2024, 05:47:10 pm
content: Turns out there are at least 3 strategies/designs for add on curve tracers.The BK 501A, which is competent has you calibrate the instrument to the scope. This allows reading the values directly from the scope.The Thaikit generates its traces in standard values which requires no calibration. The measurements are taken directly from the screen.The Heathkit has you calibrate the scope to the instrument. This means you will likely use the calibration setting on you CRT scope and you will need to use the fine adjustment in the attenuators on your digital scope. The scope graticule is now graduated to te dial settings on the Heathkit instrument. You take your readings from the dial values; the scope graticule is used to subdivide those dial values.This was pretty confusing for me. But I finally figured it out.In terms of utility:Without question, the Heathkit offers the most complete information. Once the scope is calibrated to the instrument, you can easily measure any transistor (there is a hack for enhancement MOS) and zeners and anything that can be doe with an octopus. Price is the issue.The BK501K is useful, but without specific adjustments like limiting resistors and the number of steps. Plus the HK can put out up to 200V.The Thaikit is more of a bench toy; a glorified TCLR tester. With no variable sweep, it cannot do zeners. It is limited to 10 or 15 volts of seep that you cannot control. Completed cost easily comes to $125. Plus, there are some design faults, some can be corrected, others cannot. It seems that if you do not know the current used by a transistor (and it is high), it can blow out the actives. Can get very frustrating.I did add a voltage octopus using the 15V transformer in my Thaikit. I also mounted a GM348 on it for component ID and transistor basics. I find that TCLR very inaccurate and my only use is ID.When I compare the calculated Hfe across the 3 devices, they all agree within 5%. I believe I am most accurate with the HK; but the calibration is tricky. The Thaikit is much more accurate than the GM348.I created a Setup in the Siglent for the HK. My Doc Brown/McGiver Thaikit stays on the bench for convenience, the HK will come out only when I need (?) it.If you are careful with what you put into the Thaikit, and only use small transistors, the Thaikit is good and has a small footprint. (about 1/2 the HK or BK). If you want an almost full curve tracer w/o the footprint of a standalone, get the Heathkit. For the cost difference, I do not see the value of the BK compared to the Thaikit w/ octopus enhancement or the Heathkit. The BK is useful for matching and service work, but it does not allow the kinds of measurements that can be done with the HK.

author: rhb
author_rank: Super Contributor
timestamp: March 30, 2024, 06:24:51 pm
content: DSO, ramp generator and PSU.Do a sweep in single shot mode and store it. Repeat at multiple base voltages.Overlay tracesHave Fun!RegBTW Good topic! I'd never thought of doing that before. Super easy with minimal kit.

author: mawyatt
author_rank: Super Contributor
timestamp: March 30, 2024, 06:57:44 pm
content: Here's link for those that want to play around with crude Curve Tracer using a DSO and AWG, plus a couple resistors.https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/Someone just did this with the new 12bit DSO, but can't find link.Best,

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 30, 2024, 11:53:55 pm
content: Quote from: rhb on March 30, 2024, 06:24:51 pmThis, or something along those lines. A beginner/hobbyist doesn't need a dedicated curve tracer, more common multipurpose tools they may already have can easily be set up as needed to provide equivalent function. With more flexibility for that matter, PSU is the main limiting factor, tubes, high power parts, etc. are a possibility.I think you could even use an analog scope with a digital camera pointed at it.

author: watchmaker
author_rank: Unknown
timestamp: March 31, 2024, 01:32:45 am
content: I am not sure where I fall on "need". Probably more toward the want side of the scale.As a 40 year watchmaker, I can offer that you need to plan ahead for where you want to go. I bought many esoteric tools for peanuts back when mechanical watches were supposedly killed off by quartz. Today these things (especially my wheel and pinion cutters)are impossible to find and much sought after. Plus it takes several years to learn how to use a machine tool well.I will say that the Thaikit furthered my education and made me make a deep dive into curve tracers, counter ckts and sweep ckts. Plus power issues.I also got competent in scope calibration, impedance matching, setups of an CRT and digital scope, etc. Trying to control those variables while juggling an ARB, PSU and camera would have just been too much.I just purchased the HK as a buy it now for $140. The seller was an excellent craftsman and he even archivally repaired a solder iron burn on his manual.In my business, I preferred to have setups that made it convenient to do something. I am the kind of guy that has a complete set of allen keys mitotuyo mics and tweezers, etc at each station not within a seat scoot. When I was doing serious restoration, I had WW lathes permanently setup fo wheel cutting,pivot polishing, and turning. I hate reconfiguring equipment and I HATE looking for tools, misplaced or not.So the use of ARB, pics and overlays would never be my approach and cause me to forego what I might learn as too much of a hassle.The other I learned in my career was to buy "obsolete" material and to start out keeping it organized. I bought bulk lots of basic material (like jewels, opinions and mainsprings) some of which cannot be had today at any price.As a result, I bought several "grab bags" or "mixed lots" of ECG/Philips/Sylvania semiconductors along with the reference manuals for semis and ICs. This way I have one system for inventory and I know where things are. And yes, they are kept in the boxes and in order.Probably this and my watchmaking are manifestations of the same sickness.

author: rhb
author_rank: Super Contributor
timestamp: April 03, 2024, 09:24:01 pm
content: Quote from: BrokenYugo on March 30, 2024, 11:53:55 pmThe classic DIY was a TTL staircase generator (Don Lancaster), half wave rectifier with 60 Hz staircase steps feeding an analog scope synced to the powerline.The Peak DCA75 will curve trace, but is painfully slow. I have an HP 4145A and Tek 477, but I don't understand why we don't have a really good $50 curve tracer. Read the Tek manual on curve tracing and you'll see how simple it isHave Fun!Reg

author: RoGeorge
author_rank: Super Contributor
timestamp: April 04, 2024, 05:17:42 am
content: w2aew has a video with an interesting staircase generator, all analog (schematic at minute 1:10):#231: Circuit Fun: Stairstep generator using 555 and op ampshttps://youtu.be/Kqb5zcrgv7s