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Jeff Liebermann <jeffl@cruzio.com>: Jan 27 10:52AM -0800 >Reason is the acrylic UV can only set with direct UV, and it doesnt >stick like epoxy anyway.. but it is ok for some materials mostly >transparent for obvious reasons.. C+   Compliments of Google search. I don't have any experience with any of these: <https://www.epoxies.com/products/uv-curable-illumabond/> <https://www.epotek.com/products/uv-and-uv-hybrid-epoxies/> <https://www.threebond.co.jp/en/product/search/?form=category-form&category=Adhesives&featuresfunctions=UV%20curing+UV-LED%20light%20source-curable> <https://www.polymer-g.com/uv-led-curable-products/uv-led-curable-epoxy/> More: <https://www.google.com/search?q=uv+curing+epoxy>   I looked for something on eBay (US) and only found small bottles, with gaudy labels, claiming to be epoxy, but more likely to be acrylic like the stuff you purchased. Searching for UV cure resign produced more of the same. I didn't see any industrial grade products, just lots of jewelry and arts+craft products. No clue what's available in UK, but I suspect that you might need to purchase it from the manufacturer or distributor.   I don't know your application, but you might look at 3D printing UV curable resin: <https://www.google.com/search?q=3d+printing+uv+epoxy> The problem is that I can't tell in most products whether "resin" refers epoxy, acrylic, urethane, or something else.   Good luck.   -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558

liz@poppyrecords.invalid.invalid (Liz Tuddenham): Jan 28 09:21AM > further done or measured but the potential is definitely there to DIY.. > Might try again with slow set epoxy where an instant semi cure would be > really useful! Thanks again. C+   See if you can beg some that is reaching its end date from your dentist.     -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk

Chris Jones <lugnut808@spam.yahoo.com>: Jan 28 10:55PM +1100 On 28/01/2022 21:38, Charlie+ wrote:   > Hi Liz - now that is a good interesting suggestion - got an appointment > on the 31st, I'll ask then! Also brings forth the thaught of mixing > acrylic UV with glass isonomer as a trial route!! Thanks. C+   What is the green stuff used for solder mask? That is UV-curable and perhaps it is epoxy. LPKF sells it in little packets like they use for ketchup or mustard in a fast food restaurant (but much more expensive I bet...) also it is green by default.

liz@poppyrecords.invalid.invalid (Liz Tuddenham): Jan 28 01:44PM > perhaps it is epoxy. LPKF sells it in little packets like they use for > ketchup or mustard in a fast food restaurant (but much more expensive I > bet...) also it is green by default.   I seem to remember it smelt like epoxy when I tried soldering through it.     -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk

liz@poppyrecords.invalid.invalid (Liz Tuddenham): Jan 28 01:44PM > Hi Liz - now that is a good interesting suggestion - got an appointment > on the 31st, I'll ask then! Also brings forth the thaught of mixing > acrylic UV with glass isonomer as a trial route!! Thanks. C+   I think dentists use epoxy for some repairs and acrylic for others (judging by the smell) so you will need to check that you get the right one.   -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk

Jake T <jaketbone@steak.com>: Jan 28 08:36AM -0500 Hi. I currently have access to a compressor/ expander IC:   https://pdf1.alldatasheet.com/datasheet-pdf/view/65260/HYNIX/GL6552.html   I want to bypass the expander during testing. Page 3 there describes each pin function. Pin 6 is "EXP Mute." It says for "L" state, expander mute is executed; for "H" state, expander is executed. Does this mean simply grounding pin 6 if I want to bypass the expander?   Thanks.

Chris Jones <lugnut808@spam.yahoo.com>: Jan 28 10:37PM +1100 On 27/01/2022 16:15, Mike S wrote:   > I was thinking the same thing. When I was a tech we used silver, and > gold conductive epoxy to attach surface mount components. Once cured it > was quite strong.   I like Creative Materials 125-15 conductive ink, but I can't recommend it for this situation because the minimum order quantity is much too large, and it has to be shipped and stored refrigerated, which makes the freight expensive. It also needs to be cured at high temperature to make it conductive (80 degress C will do but hotter is better). It isn't mechanically strong at all, but it is very conductive and in practice has a long shelf life if kept refrigerated, and is a one-part ink so I can dispense small quantities with little waste.   For this job, the stuff for fixing windscreen de-misters ought to do and is more widely available.   I think the carbon-based ink (Bare Conductive etc.) would not do for a crystal oscillator, the resistance would be too high and it would hurt the Q.

Charlie+ <charlie@xxx.net>: Jan 27 05:46PM On Thu, 27 Jan 2022 03:10:21 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote as underneath :   > the curing process and final properties differ.   >Full disclosure: I've worked with UV curable cyanoacrylate adhesive, >but not epoxy.   Thanks JL yes I know what I've already got! Acrylic - I needed a source for genuine UV Epoxy as opposed to the sales speak epoxy which is'nt! Reason is the acrylic UV can only set with direct UV, and it doesnt stick like epoxy anyway.. but it is ok for some materials mostly transparent for obvious reasons.. C+

Charlie+ <charlie@xxx.net>: Jan 28 08:26AM On Thu, 27 Jan 2022 10:52:51 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote as underneath :   snip >The problem is that I can't tell in most products whether "resin" >refers epoxy, acrylic, urethane, or something else.   >Good luck. JL Thanks some great links you found, much better than I managed to find.. my education on the subject improves! So I surmise: Only industrial sources and prices - out of bounds for my uses! Ultra short shelf life. Hours/Days only. Probably actually made from hybrid acrylic/epoxy mixes.   Funnily enough the first thing I tried within a few minutes of getting the eBay stuff and realizing it had no epoxy characteristics, was to mix some with 5 min epoxy. Fully expecting it to be immiscible, amazed to find it mixed fine and worked as a first shot experiment, semi cured with UV 365nM immediately and set solid after elapsed time! Nothing further done or measured but the potential is definitely there to DIY.. Might try again with slow set epoxy where an instant semi cure would be really useful! Thanks again. C+

Charlie+ <charlie@xxx.net>: Jan 28 10:38AM On Fri, 28 Jan 2022 09:21:23 +0000, liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote as underneath :   Snip >> Might try again with slow set epoxy where an instant semi cure would be >> really useful! Thanks again. C+   >See if you can beg some that is reaching its end date from your dentist.   Hi Liz - now that is a good interesting suggestion - got an appointment on the 31st, I'll ask then! Also brings forth the thaught of mixing acrylic UV with glass isonomer as a trial route!! Thanks. C+

Phil Allison <pallison49@gmail.com>: Jan 27 03:14PM -0800 BboB wrote: ============= > the amount of hiss, I don't think I'm going to be able to use this for > the intended purpose.   > I welcome any suggestions here to solve this.   ** You sure the frequency is clear ?   You might have a conflict with a DTV station.     ..... Phil

BboB <electronix@ourd.net>: Jan 28 04:54AM -0500 On 1/27/22 06:49, Peter W. wrote:   > Without being judgmental, I never purchase anything from 'the bay' on the expectation that it actually works as described. Nor would I sell anything (a very rare occurrence) that I describe as 'working'.   > Peter Wieck > Melrose Park, PA   What this turned out to be was somehow caused by the preamp. I switched out the preamps and problem solved. There must be instability in the original preamp somewhere. You were right, definitely audio related. Thanks for the help.

Jeroni Paul <JERONI.PAUL@terra.es>: Jan 27 07:04PM -0800 I have an HiFi system SABA CT9810 (also sold as THOMSON VTM 2800/2900, CRK 1207, BRANDT MID 3000, TELEFUNKEN POWER PACK 200) where the volume control does not allow low enough volume levels, the first step sounds normal volume, the second is quite loud and above too loud for domestic use. It was like this when new, not a fault but a design issue. It uses a pair of LC7533 for digital volume control and a LA4280 power amplifier.   LA4280 circuit is exactly as depicted in its datasheet. Years ago I lowered its gain inserting 1K8 resistors in series with the capacitor at the feedback pins and now I decided to lower it even more with 4K7 resistors. That works and results in a much better volume control range but now I get strange squealings tuning AM radio.   LA4280 datasheet explains nothing but LA4270 datasheet says to insert these resistors to lower the gain, but recommends to keep it above 30dB. That would be 700 ohm resistors, I have gone much lower gain and it is now prone to oscillate with the AM radio. The rest of the functions sound fine (FM, phono, tape, aux) but I wonder if it could be oscillating anyway.   Of course I would like to find the schematic of this thing to know how it was supposed to work but couldn't find anything. This one could be some prototype unit or something. I don't find any fault or wrong/missing component, the circuits are built and work as per datasheet, it's just that seems incorrectly designed.   The LC7533 is fed with 1Vpeak line-level audio from the selector and it adjusts that from an almost invisible scope trace to the full 1V input. Its output goes straight to the LA4280 and a led vu-meter that displays within reasonable range, this is why I think the amplifier input has the intended level. The LA4280 has a gain of 100 that to me is way too high, a gain of 10 or lower would seem more reasonable.   So some questions. The LA4280 has two unused pins "Phase compensation", could these be used to make it stable at lower gains? Any other idea? Maybe a resistor divider at the input? (I would have to add an extra coupling capacitor for that).

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