I've been working on a power supply for antique Teletype selector magnets. These need 120VDC 60mA for the first 2ms or so of each bit time,...

I've been working on a power supply for antique Teletype selector magnets. These need 120VDC 60mA for the first 2ms or so of each bit time, but the sustain voltage needed is only 3-4V. So I've built an isolated boost supply and interface board, all powered from a USB port. The whole project is on Github: https://github.com/John-Nagle/ttyloopdriver where there's an explanation of how...

This is a 200 watt isolating dc/dc converter: https://www.dropbox.com/s/9k0oe2rc67mmvc1/23S941A_iso_ps.pdf?dl=0 Some idiot who shall not...

This is a 200 watt isolating dc/dc converter: https://www.dropbox.com/s/9k0oe2rc67mmvc1/23S941A_iso_ps.pdf?dl=0 Some idiot who shall not be named figured that we could start it up by ramping up the drive pulse widths from the FPGA, starting very small and eventually making square waves. But even small pulses pull hundreds of amps and have side effects like deconfiguring the FPGA. The...

This will have to work at up to 200 watts maybe; 48 in and out. Those surface-mount Coilcraft planar transformers are wonderful....

This will have to work at up to 200 watts maybe; 48 in and out. Those surface-mount Coilcraft planar transformers are wonderful. https://www.coilcraft.com/en-us/products/transformers/planar-transformers/planar/pl300/ I suspect some air flow can sneak in between the flat kapton windings. I guess I should include the leakage inductances, but they are tiny. The LTC gate drivers are ...

Hi all,   I'm following a group discussing building a Q meter. HP has a two transistor Impedance Converter Ass'y. >...

Hi all,   I'm following a group discussing building a Q meter. HP has a two transistor Impedance Converter Ass'y. > https://www.dropbox.com/s/n5gj8powzph6611/HP4342A%20impedance%20converter%20and%20injection%20tr ansformer..jpg?dl=0 One builder got down to 0.86? output impedance at 50kHz, 1.05? at 1MHz, on up to 7.70? at 30MHz after trying several common transistors for the first trans

I want to use the RPI to process the incoming data from five crystal microphones in order to obtain the direction of arrival of sound so that i...

I want to use the RPI to process the incoming data from five crystal microphones in order to obtain the direction of arrival of sound so that i can steer a camera mounted on two servos to that direction. Since there is no audio inputs to the RPI i think of using a two-channel analog to digital converter, one channel is connected to a refrence mic and the other channel is connected to the out...

Hello, Due to the used RMS converter low level AC measurememts with this DMM are less precise to incorrect. There is a lab note as to this...

Hello, Due to the used RMS converter low level AC measurememts with this DMM are less precise to incorrect. There is a lab note as to this problem by Gellerlabs containing three pictures. I have this note which, unfortunately, lacks the mentioned pictures. And, unfortunately too, the link to this note doesn't work any more. Has anyone

So I built this board for my fire prevention equipment customer. (An excellent outfit BTW: Argus Fire Control.) It needed two isolated...

So I built this board for my fire prevention equipment customer. (An excellent outfit BTW: Argus Fire Control.) It needed two isolated 5-V supplies, one for the analogue stuff and one for RS-485. A few months ago we were discussing those supplies in this very boutique, in the "Coupled Inductors--how coupled is coupled?" thread. I wound up with a flybuck design using an LM3103 sync buck c...

First, some background. I have designed an SCR trigger board using an IRS24541 self-oscillating FWB driver and two dual MOSFETs FDS6930B...

First, some background. I have designed an SCR trigger board using an IRS24541 self-oscillating FWB driver and two dual MOSFETs FDS6930B (30V, 5A, 0.055 RdsOn, 2W). I made a couple of transformers using EPCOS E187 or E16-8-5 cores with N27 ferrite having an Al of 950 nH. I used about 20 turns of #32 AWG wire on both primary and secondary, to get 12 VDC out with 12 VDC input. Running at ...

Hi I am working on a high frequency design in which we in principle is using a very high frequency switch mode converter I need low loss, so...

Hi I am working on a high frequency design in which we in principle is using a very high frequency switch mode converter I need low loss, so need to minimize capacitive parasitics, and also minimize inductances. They conflict of course, smaller trace has lower capacitance but higher inductance. We use Altium for layout and have used ADS for parasitic extraction. But we cannot afford the l...

I'm interested in making a load cell scale using an Arduino so I can program special features that currently available scales don't...

I'm interested in making a load cell scale using an Arduino so I can program special features that currently available scales don't have. Any thoughts on best way to get high resolution data to an Arduino microcontroller board? AD7730 chip, or Instrumentation amp to A/D converter? Anything readily available such as load cell in and serial data out? Most of the ready made load c...

Hi So I wanted to check the VCE of a transistor in a small converter running at 100kHz, expected to see about 100mV above ground as...

Hi So I wanted to check the VCE of a transistor in a small converter running at 100kHz, expected to see about 100mV above ground as the saturation voltage of the NPN, increasing linearely since magnetising current increasing. I saw nothing like that, debugging and found the scope (Tek DPO5000) somehow saturates with high voltage inputs. The signal is a square wave of 100kHz, 25V peak to...

Hi all. I need a basic voltage mode PWM controller for a buck converter project. I need a wide duty cycle range, like 5 - 95%. I don't need an...

Hi all. I need a basic voltage mode PWM controller for a buck converter project. I need a wide duty cycle range, like 5 - 95%. I don't need an error-amp in the ic, since this part is placed elsewhere in my circuit. So, a basic Ramp generator and a PWM comparator, and an output stage. An UC3843 would suit if it were voltage controlled instead of current. I've gone through Fairchild, ONsemi we...

Dear All, I am now making a 48 V to 120V Boost Converter (with a single series 560uH 10A inductor) using PWM IC SG3524, and I am a little...

Dear All, I am now making a 48 V to 120V Boost Converter (with a single series 560uH 10A inductor) using PWM IC SG3524, and I am a little bit confused with the use of error amplifier input pins (pin 1 and pin 2) and the compensation pin (pin 9). A typical example application circuit (see figure 13) divides the reference voltage 5V to 2.5V, and feeds it to pin 2 as reference. The output is ...

Hi, The input DC voltage is in the range of 1.2 volts to 40 volts. I need 3.3 volts output and 300mA. So. I decided to use LT3759. LT3759's...

Hi, The input DC voltage is in the range of 1.2 volts to 40 volts. I need 3.3 volts output and 300mA. So. I decided to use LT3759. LT3759's data sheet is at the following link http://cds.linear.com/docs/Datasheet/3759fa.pdf Plan is to configure the LT2759 to generate 5 volts @ 300mA and then use LT 1962 to generate 3.3 Volts at 300mA. 300mA is maximum but load will work between 150mA to...

This is an about -30 dBu sine wave being amplified to about 0dBu by the triode section of a Sylvania 12EC8 triode/pentode "space charge" tube....

This is an about -30 dBu sine wave being amplified to about 0dBu by the triode section of a Sylvania 12EC8 triode/pentode "space charge" tube. The plate load is a single transistor gyrator/constant current source. Plate and heater currents are being supplied by a "China Special" boost converter module that's stepping up a 4 "C" cell battery pack. http://tinyurl.com/zeegduc Yick. Lots...

Since there haven't been enough serious design articles in a while, I thought I'd write one. Some time ago I had questions about the problems...

Since there haven't been enough serious design articles in a while, I thought I'd write one. Some time ago I had questions about the problems I encountered building a switching power supply to drive a 60mA current loop Teletype from a USB port. I wanted to power it entirely from the USB port, and finally succeeded. Here's the schematic: https://image.ibb.co/mW08yF/board2_3.png The f...

I have seen a design for a high-power (200kW) AC motor controller that uses dual-inductor AC line chokes for a DC-DC converter for IGBT gate...

I have seen a design for a high-power (200kW) AC motor controller that uses dual-inductor AC line chokes for a DC-DC converter for IGBT gate drive power supplies. http://enginuitysystems.com/pix/electronics/200kW_AC_Controller_p3.png I have found some chokes rated 500 uH and 1 amp, with 250 VAC rated isolation, for less than a dollar each: http://www.mouser.com/ds/2/212/KEM_LF0016_SU9V-...

Hello, I am trying to simulate a buck and a boost converter using Christophe Basso's generic PWM models (in LTSpice) for voltage mode...

Hello, I am trying to simulate a buck and a boost converter using Christophe Basso's generic PWM models (in LTSpice) for voltage mode controlled and current mode controlled switched mode power supplies. These models have an integrated PWM generator and power switch. These models can be found here: http://cbasso.pagesperso-orange.fr/Downloads/IsSpice/Final%20models.zip (alternati...

This is the relevant part of the schematic of an 18650 battery charger and boost converter (to 5V)...

This is the relevant part of the schematic of an 18650 battery charger and boost converter (to 5V) module: https://i.postimg.cc/Tw7X35Fq/USB-to-TP4056.jpg And here's the module: https://www.aliexpress.com/item/32870411748.html Coming from the USB power pin, there's a series Schottky diode and a very low value resistor. The resistor is found in the TP4056 datasheet typical applic...

Hi I am working on a high power frequency inverter (> 1kW) and have a "funny" looking emission graph The converter is the typical inverter...

Hi I am working on a high power frequency inverter (> 1kW) and have a "funny" looking emission graph The converter is the typical inverter type, EMC filter-> 3 Phase Rectifier-> DC Inductor-> DC Link capacitor-> 6 switch Inverter-> Motor Like this: www.electronicsdesign.dk/tmp/Inverter.jpeg We stripped down the circuits and isolated the noise to the EMC filter and bridge rectifier. T