Our power supply chokes are designed to work at 100/120Hz and with voltages around 100V. Most induction meters work at a few volts or less, at around 1kHz. This is not the correct operating point for a power supply choke, and the reading on the induction meter is usually around half the specified value of [...]
EAGLE CAD Lundahl library (created by Bob Starr of RTZ Audio): https://cadsoft.io/resources/libraries/?query=lundahl CADSoft EAGLE PCB Design Software is a CAD software available for a number of different platforms. A limited function version is available free of charge for personal use. Please see http://www.cadsoft.io for downloads.
An audio line is a cable transferring an audio signal from the output of one device to the input of another. Normally the input impedance is fairly high, >1k for mic preamps and >10k for line inputs. If the impedances in both ends of an audio line are high, any noise current picked up by [...]
I guess you are right. It _IS_ confusing. If we assume a certain DC current, there are two ways to reach a desired core operating point: 1. With a given coil, adjust the core air-gap or 2. With a given core air-gap, adjust the number of turns on the coil The type number LL1660S/18mA is [...]
I’ve built an amp with 2A3 and LL1660. I like the sound of it, but was a little frustrated when I measured the frequency response today. Around 9.5KHz I get a climbing response that doesn’t go away until I’ve reached the end of the bandwidth of the amp. With a few measurements, I located the [...]
The interesting parameter for a mains transformer is the no-load current. For our mains transformers LL1648 — 51 the no load current is less than 100mA, indicating a no load impedance above 2kohms at 50 Hz. (corresponding to 6H) The no-load current should be compared to the full-load current, which for a 250VA transformer is [...]
Gain matching and CMR would not be so good. Difference in copper resistance is due to difference in wire gauge. It is possible that we used wire from different runs or from different vendors. However, the number of turns should be correct. (I say ”should be” as shit do happens, even at Lundahls. But if [...]
The internal structures of the LL1581XL and LL1570XL are quite different. The LL1581XL is a splitting transformer with very high immunity to external noise and noise crosstalk. When used as a splitting transformer, the LL1570XL may pick up electromagnetic hum (from e.g. motrs or power supplies).
For such a low input impednace would suggesth the LL1570 used 1:2. The LL1538 are ideally used with amplifiers with around 5k optimum source impedance.
It appears that one should obtain a 50% tap in this manner. Yes, you can use the LL1620 in UL mode if you connect the screens as you describe.