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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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25th Feb 2021, 9:36 pm | #1 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Transistors from old CFL bulbs.
I was having a chucking-out and came across a box of old CFL bulbs - still working but long since replaced with LEDs.
I cut some of them open to see what was in the electronic ballast; the answer being a bunch of diodes, a small 400V-rated electrolytic capacitor, some other 1Kv-ated capacitors, a coil or two - and - in one - a couple of decently-beefy TO220 transistors. These are marked E13005 - the closest to this I've tracked down is MJE13005 - which are rated for a collector-emitter voltage of 400V, DC collector-current of 4A, Ft of 4MHz. 75W collector dissipation [with suitable heatsinking of course] Only downer is that Hfe is listed as being between 8 and 40 - so hardly spectacular! Any suggestions as to use? I was initially thinking of trying to build a transformer-coupled amplifier [imagine the classic two-OC81-in-push-pull revisioned using a valve push-pull output transistor and 250V HT] but the low Hfe makes me think this would be a fool's errand. I might just see if I can use them in a "solid-state vibrator replacement" Royer-type oscillator for one of my R209 receivers. |
25th Feb 2021, 10:41 pm | #2 |
Hexode
Join Date: Oct 2010
Location: Box End, Beds. UK.
Posts: 271
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Re: Transistors from old CFL bulbs.
High voltage transistors frequently have low Hfe. In the case of BU208 I seem to remember could be as low as 2. CFLs frequently have high voltage TO92 devices, sometimes TO126; I have yet to find TO220s
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26th Feb 2021, 12:32 am | #3 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
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Re: Transistors from old CFL bulbs.
They are Fairchild KSE13005 devices.
Similar specs to the MJE13005's. |
26th Feb 2021, 12:55 am | #4 |
Heptode
Join Date: Oct 2011
Location: Culcheth, Cheshire, UK.
Posts: 637
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Re: Transistors from old CFL bulbs.
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26th Feb 2021, 12:57 am | #5 |
Nonode
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,085
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Re: Transistors from old CFL bulbs.
Those CFLs started off with BJTs but soon moved over to MOSFETs. A wonderful source of interesting parts, but after you've struggled to strip one or two you come to realise that life's too short
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26th Feb 2021, 9:04 am | #6 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,638
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Re: Transistors from old CFL bulbs.
I'd still use the bulbs, still way better than an incandescent, if not those tranny's would make a reasonable HV CCS or could be connected with an MPS42 as a Darlington pair for extra hfe.That said I thought if used as an OP device hfe isn't that important, the voltage amplification done previously the OP device just used to shift current.
Andy.
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26th Feb 2021, 9:41 am | #7 |
Tetrode
Join Date: Sep 2020
Location: Lewes, East Sussex, UK.
Posts: 66
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Re: Transistors from old CFL bulbs.
There's an interesting article in Sprat (G-QRP), issue 138, Spring 2009 - Das DereLicht - A CW transmitter made from a light bulb. You need a crystal and a few components for the output LPF and the others come from the bulb. He found a BUL128B transistor in the bulb. The transmitter produces up to 1.5w on 80m. Neat!
Best wishes Des |
26th Feb 2021, 8:55 pm | #8 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Transistors from old CFL bulbs.
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26th Feb 2021, 9:52 pm | #9 | |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: Transistors from old CFL bulbs.
Quote:
An insight into an application of an HF version of the Baxandall-modified Royer oscillator, though, so sort of educational. The one time I bothered with component reclamation was on finding a few hundred NOS installation-type CFL drivers in a skip on an industrial estate, things about the size of two fag-packets with a screw-hole at each corner and a choc-strip along one edge- each had a RIFA 6.8uF 450V 125 degree axial elko with long leads, these were harvested and feature in various things here. Even so, I doubt they'd be more than about a quid each. (They also featured a pair of the afore-mentioned E13005 devices, presumably made by the gazillion for this market). |
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27th Feb 2021, 3:33 pm | #10 |
Heptode
Join Date: Nov 2009
Location: London, Ontario, Canada
Posts: 672
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Re: Transistors from old CFL bulbs.
Some time ago I was given a non-working service type SA, a Cushman CE-15.
https://www.radiomuseum.org/r/cushma...tor_ce_15.html One of the horizontal amp's final transistors was faulty. A transistor salvaged from a faulty CFL-light was a good match for the other transistor. If I remember correctly the beta was around 30 or so. It is still working fine. Peter |
27th Feb 2021, 4:02 pm | #11 | |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
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Re: Transistors from old CFL bulbs.
Quote:
David |
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27th Feb 2021, 9:05 pm | #12 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: Transistors from old CFL bulbs.
Maybe I should have stuffed the lot in the boot- with hindsight, it's the sort of thing I would have done if only to pass on the bulk of such good caps to others as a favour. I didn't have the brass neck to take more than about a dozen- it's the "funny looks" thing! You're right, the higher voltage PEG124s are only rated to 105 degrees, rather than the 125 degrees of the lower voltage series,
Colin |