ฝัง
- เผยแพร่เมื่อ 30 ก.ค. 2015
- Following on from the Transistor / Component Tester review and teardown video, I briefly introduce germanium transistors and see if they can also be tested with this cheap transistor tester.
See the teardown and review of the eBay tester here:
• Transistor / Component... - วิทยาศาสตร์และเทคโนโลยี
The germanium transistors were well known for wide range values. Also, the leakage test always tested high, particularly on power germanium transistors, but would operate normally as they were designed to do.
+John Cunningham good insight, thanks for your feedback :)
I replaced an AC132 with one of these in an audio amplifier (driver stage), where the emitter-collector voltage measured nil.. (power on in circuit). These transistors were susceptible to what is called 'tin whisker', where a metal 'dendrite' forms across the PN-NP junction, shorting out the collector and emitter. In the periodic table, Germanium is classed as a metal (quadravalent), where Silicon is not, but also quadravalent..
I've heard of tin whiskers potentially being an issue with some lead-free solders. I didn't know it was an issue with germanium. Something new I learned today :) Thanks for the comment.
+NearFarMedia Seems to be with the method of connection internally, but as you mentioned, the variation in characteristics is somewhat greater in Germanium types; you tested 2 at room temperature, but increase that by say, 10 degrees, and you may find a reversal of the Hfe data... so a lot of extra passive components were required to get stability (emitter resistors, thermistors) but much success was enjoyed with their use and efficiency compared to vacuum tubes (valves). A 'failure event' of a germanium transistor used within data sheet parameters is very rare indeed, as the equipment I repaired was 40 years old... and the fault possibly started with the AC 132 being 'noisy' (sounding like a scratchy record), at which point it would have tested ok... good for an oscillator... BTW, a very good presentation on the AC128..
thank you very much......not bad for a cheap tester...much obliged
i like the way germanium transistors sound they sound notice-ably warmer than silcon
sir could you tell me what is the substitute of ac187. i mean to say i have a mini portable turntable so its amplifier include two transistor ac188 and ac187. but ac187 i couldn't found any shop help me
The problem with this tester looks like it doesn't account for leakage. Leakage must be deducted from the current gain to get an accurate gain measurement and can also be very high and cause thermal run away if the leakage is too high. The tester looks good, but i definitely wouldnt trust it for germanium transistor gain measurements if it doesn't report leakage. (good video btw). Edit: i would suggest a peak atlas 55 or 75 or following the geofex germanium transistor tester circuit. Cheers
+DIY Guitar Pedals All good points. I agree that this tester has a place for low cost hobby use, but certainly has its limitations. There are much better test and measurement devices for accurate or serious applications.
Generally I use this tester as a guide when sorting parts, or too double check values.
Thanks for your suggestions too!
The newest microchips + transistors will work with light. (lightspeed) and you develop a new transistor wich works with electricity.. That is a good idea
does this guy only do audio in the left channel?
+Thomas Brown Sorry about that! I didn't use headphones in the edit and missed the audio issue. (>
I hv 1kg germnium metal