ISOLATED AC CURRENT MONITOR
This circuit uses a small AC current transformer from Magnetek to produce an isolated voltage proportional to the AC current in the primary winding. The transformer contains a single turn primary with a low 0.001-ohm resistance. It can easily handle 30 amps of AC current and provides at least 500vac of isolation. With the components shown, the output AC voltage is scaled so 1 amp of current produces 100mv of AC voltage. |
Everything you wanted to know about wideband, low-frequency transformers:
EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit. |
| External Isolation Transformer Box: designed for Mackie and other Mixers Eliminates RFI Problems |
| Grounding & Shielding: describes basic audio transformer uses like balanced in/out and signal splitters |
| High CMRR Balanced Interface: Uses for Crystal18 or20 Bit A/D Converters. This is a PDF file |
| High Output Line Driver for Single Ended Power Supply: PDF file |
| IC Mic Preamp uses Jensen Twin Servo topology: |
| Interconnection of Balanced & Unbalanced Equipment: 4 page booklet in PDF format |
| Internal Modification to Mic Inputs of the Mackie 1604 Mixer Eliminates RFI Problems: adding transformer isolation increases common mode rejection and eliminates RF interference, PDF document |
| Isolation Transformer Passes millihertz Signals: EDN-Design Ideas |
| IT 4 Four Channel Isolation Transformer unit: audio signal isolation transformer, product datasheet with circuit diagram in PDF format |
| IT one inline 600 / 600 Ohm Line Transformer: audio signal isolation transformer, product datasheet with circuit diagram in PDF format |
| Jensen Direct Box Transformers: data sheets have example circuit diagrams |
| Jensen Transformers Application Schematics: includes many microphone preamplifier related |
| JP 11P 1 Input Transformer Improvement for Electronically balanced Input: |
| JS 11SPP 6M 600 Ohm Line Isolator with Line termination Switch: for used with long 600 ohm lines that need termination |
| JS 11SSP 6M 150 Ohm Line to 600 Ohm Load application: isolation transformer with impedance conversion |
| JT 10B D Used in Line Level 2 Way Splitter / Isolator: active line level splitter circuit with input and output isolation |
| JT 10KB D & JT 6110K B "Pro" to "Consumer" Interfaces: from +4dBu balanced output to -10dbV consumer equipment input |
| JT 10KB D & JT DB E Provide "J Box" Consumer to Studio Interfaces: from -10dBV unbalanced to150 ohm balanced microphone level -45dBu signal and from +4dBu balanced signal to -10dBV unbalanced signal |
| JT 10KB D Isolates & Converts Speaker Drive to Line Level: |
| JT 11 BM High Level Differential IC Output Stage with DC Servo: |
| JT 11 BM High Level High Current Differential Output Stage with DC Servo: |
| JT 11 DM Basic Hum Stopper Transformer Isolation Box: simple isolator for 600 ohm balanced audio lines |
| JT 11 DM Converts Unbalanced Output to Balanced: |
| JT 11 FL Isolates & Converts Guitar Amp Speaker Out to Line Output: |
| JT 11 FL provides Isolated Line Output from Guitar Amplifier: |
| JT 11 YZPC in Unbalanced Long Line Driver / Isolator: |
| JT 11B 1 + "Phantom" Buffer Provide Balanced Guitar Output: |
| JT 11P 1 as "Phase Splitter" with Symmetrical Outputs: |
| JT 11P 1 Balanced Tube Line Input Stage: |
| JT 11P 1 Conversion of Unbalanced Input to Balanced: |
| JT 11P 1 in 2 Way Passive "Guitar Splitter": from one guitar to2- guitar amplifiers |
| JT 11P 1 in 4 Way Active "Guitar Splitter": from one guitar to up to4 guitar amplifiers |
| JT 11P 1 Unbalanced Automotive or Consumer Application: isolation transformer box for unbalanced consumer audio line signals |
| JT 11P 1 used as Unbalanced Polarity Inverter: passive transformer based audio signal inverter circuit |
| JT 11SSP 6M 600 Ohm Line Isolation Application: isolation transformer for 600 ohm balanced audio line |
| JT 11SSP 6M as Input Transformer for Crystal CS5367 A / D Converter: transformer balanced passive input circuit for CS5367 A/D converter, PDF file |
| JT 11SSP 6M Bi-Directional Lo Z Long Line Application: this circuit isolated and impedance matches less than100 ohm source to long cable line and that to over10 kohm input |
| JT 11SSP 6M Passive Stereo Matrix for M S Mic Technique: |
| JT 11SSP 6M Universal Patchbay Isolation Application: for use with professional low impedance sources and high impedance loads |
| JT 123 BL High Level Low Impedance Differential Output Stage with DC Servo: |
| JT 123 S Line Driver with Feedback Around the Transformer: |
| JT 13K6 C in Simple 1 IC Stage Mic Preamp: 15KB PDF |
| JT 16 A Improves Performance of SSM2017 Mic Preamp IC: |
| JT 6110K B at Input Stage for Crystal a to D Converters: high performance transformer balanced input stage for Crystal A/D converters, PDF file |
| JT 6110K B Isolates "70 Volt" Line & Converts to Line Level: |
| JT DB E "Direct Box" for very High Level Signals: takes high level line signal and outputs balanced microphone level signal |
| JT DB E Converts Consumer Stereo Inputs to Mono Balanced Mic Output: |
| JT DB E Full featured "Direct Box" Application Schematic: |
| JT DB E Standard Musical instrument or Synthesizer "Direct Box": |
| JT MB C "Real" Mic Inputs & Phantom Power for Sony DAT: |
| JT MB C in Low Noise, High Isolation Line Receiver for Low Z Sources: |
| JT MB C Isolates both Mic & Line Inputs of inexpensive Mixer: |
| JT MB C Mic Input Isolation for Mackie Mixers: |
| JT MB C Used to "Phantom" Power the Realistic PZM Mic: |
| JT MB D Converts 600 Ohm Unbalanced Mic to 150 Ohm Balanced Mic Line: |
| JT MB D Passive Stereo Matrix for M S Mic Technique: |
| Method sets voltage in multiple-output converters: EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit. |
| Mixed Feedback Drive for Audio Output Transformers: Technical paper from Lundahl Transformers in PDF format |
| Power Supplies & Transformers: Basic structures of power supplies |
| Power Supplies and Regulators: new low power discrete switcher |
| Step Down Rectifier makes a Simple DC Power Supply: 04/09/98 EDN-Design Ideas - A simple and useful nonisolated rectifier features voltage step-down operation, acceptable Class A line-current harmonics, inherent short-circuit protection, and, optionally, a regulated output |
| Theory & Construction of Mic "Splitters": 5 page booklet in PDF format |
| Transformer Coupled Splitter: Active amplified transformer isolated signal splitter that enables hum-free connection of1-guitar to more than1-amp as well as having a direct output |
| Transformers for Audio Interfacing: Discussion on using audio transformers in equipment interconnections, read also Line-level transformers in High-End Audio |
