The shutdown pop on the LM1875 is only small and not annoying (3000uF to 4700uF per rail). It's odd that it doesn't happen with the fake chips supplied with the kit.
hi
no. no new measurements from this kit.
AFAIK this picture shows john audio tech´s method to measure:
1khz main tone and the 3khz or 4kHz pilot tone which is 1% of the 1khz tone.
so you can better look at the the pilot signal especially at pushing more power...
chris
no. no new measurements from this kit.
AFAIK this picture shows john audio tech´s method to measure:
1khz main tone and the 3khz or 4kHz pilot tone which is 1% of the 1khz tone.
so you can better look at the the pilot signal especially at pushing more power...
chris
In fact, I see the 2nd harmonic dominant with 60mv rms for 18.4 fundemantal. This gives 0.32% at 40w.
This how to recognize the original LM1875
I am shopping for the IC, and I couldn't find any directives on this site to get for sure original ones. So I share my investigation.
An excellent website is LM1875 manual with 100% guaranteed detection of a fake chip.
UTC manufactures also genuine ones under D1875 old versions and LM1875L new. Both have also fake ones. TI has old version with big letters in the center, forget it, and the new version with small letters on the top.
Looking on pictures, I noticed that the original new one, not the old has non-uniform upper tab
and the back is wide and rectangular. On Aliexpress I found only one proposition for 18$/10pcs, to know that TI sells 1190$/1000pcs.
I am shopping for the IC, and I couldn't find any directives on this site to get for sure original ones. So I share my investigation.
An excellent website is LM1875 manual with 100% guaranteed detection of a fake chip.
UTC manufactures also genuine ones under D1875 old versions and LM1875L new. Both have also fake ones. TI has old version with big letters in the center, forget it, and the new version with small letters on the top.
Looking on pictures, I noticed that the original new one, not the old has non-uniform upper tab
and the back is wide and rectangular. On Aliexpress I found only one proposition for 18$/10pcs, to know that TI sells 1190$/1000pcs.
Farnell, Digikey, Mouser and RS Components have genuine stock.
LM1875T/NOPB | LM1875T/NOPB Texas Instruments, Audio Amplifier 5.5MHz, 5-Pin TO-220 | RS Components
https://nz.element14.com/texas-instruments/lm1875t-nopb/ic-op-amp-single-70khz/dp/3116856?ost=lm1875
Search results for: LM1875 – Mouser New Zealand
Blocked
LM1875T/NOPB | LM1875T/NOPB Texas Instruments, Audio Amplifier 5.5MHz, 5-Pin TO-220 | RS Components
https://nz.element14.com/texas-instruments/lm1875t-nopb/ic-op-amp-single-70khz/dp/3116856?ost=lm1875
Search results for: LM1875 – Mouser New Zealand
Blocked
Very high shipment cost. mouser for my region is 20$ bellow 60$ order. The 18$/10pcs is free shipment. You can buy directly from TI for more than 6$ shipment.
I just pad out mouser/digikey orders with other parts I know I will use to get it over the threshold for free shipping.
Mouser has an extensive range of Vishnu/dale cmf/rn series resistors which is about all I use except for high power
Mouser has an extensive range of Vishnu/dale cmf/rn series resistors which is about all I use except for high power
Mouser does not offer free shipping in USA , Newark wants 150$ spent in order to get free shipping , plz don’t buy your chips from AliExpress !!!!
That seems ridiculous, free shipping all the way across the pacific to little old New Zealand but no free shipping domestically? That strikes me as the opposite of normal....
i wrote in some pages before...as i remember...
Digikey 20 pcs 52 euro + VAT and deliver...---> 66 euro
International shipping in the time of Covid.....
I do hope it turns up soon, I want to see how goes on your test bench.
I do hope it turns up soon, I want to see how goes on your test bench.
Hi Denis
i bought the same...important is that it is dual = +/- 24V etc.
.i what tot try a SMPS vs unregulated power supply...
dual group output +-24V and DC12V 300W power board MX50 L20 audio amplifier board power supply instead toroidal transformer|AC/DC Adapters| - AliExpress
chris
i bought the same...important is that it is dual = +/- 24V etc.
.i what tot try a SMPS vs unregulated power supply...
dual group output +-24V and DC12V 300W power board MX50 L20 audio amplifier board power supply instead toroidal transformer|AC/DC Adapters| - AliExpress
chris
I have only powered up the SMPS to see that the voltages measure correctly, I have not put it under load, but it makes a funny sound.
Does yours make a funny sound? A high pitched sound?
Thank you,
David.
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