## How to wind Toroids

Posted by: Sarah

On: 02 Sep, 2020

Viewed:265 times - 1 day, 19 minute, 59 second ago

Category:

Rating:
3.8
83 out of 100 based on 208 user ratings

In this chance we want to post how to wind Toroids may this explanation will help you to understand.  The effective inductance of a toroids coil or a transformer winding depends in part on the distributed capacitance between the coil turns an...

In this chance we want to post how to wind Toroids may this explanation will help you to understand.  The effective inductance of a toroids coil or a transformer winding depends in part on the distributed capacitance between the coil turns and between the ends of the winding.  When a large number of turns are used (for example 500, 1000), the distributed capacitance can be as great as 100 pF.  Ideally, there would be no distributed or parasitic capacitance, but this not possible. Therefore, the unwanted capacitance must be kept as low as possible in order to take proper advantage of the Al factor discussed earlier in this section. The greater the distributed capacitance, the more restrictive the transformer of the inductor becomes when applied in a broadband circuit. In the case of a narrow –band application, the Q can be affected by the distributed capacitance.

Fig. 70 – (A) Illustration of a homemade winding shuttle for toroids. The wire is stored through the center hole of the toroid, again and again, until the required number of turns is in place.(B) it is best to leave a 30° gap between the ends of the toroid winding. This will reduce the distributed capacitance considerably. (C) Edgewise view of a toroid core, illustrating the method for counting the turns accurately. (D) The low-impedance winding of a toroidal transformer is usually wound over the cold end of the main winding.

The pictorial illustration in Fig. 70B shows the inductor turns distributed uniformly around the toroid core, but a gap of approximately 30 Celsius is maintained between the ends of the winding. The closer the ends of the winding are to one another, the greater the unwanted capacitance. Also, in order to closely approximate the desired toroids inductance when using the Al formula, the winding should be spread over the core as shown. When the turns of the winding are not close wounds, they can be spread apart to decrease the effective inductance (this lowers the distributed C). Conversely, as the turns are pushed closer together, the effective inductance is increased by virtue of the greater distributed capacitance. This phenomenon can be used to advantage during the final adjustment of narrow-band circuits in which toroids are used.

The proper method for counting the turns on a toroidal inductor is shown in fig. 70C. The core is shown as it would appear when stood on its edge with the narrow dimension toward the viewer. In this example, a four-turn winding has been placed on the core.

Some manufacturers of toroids recommend the windings on toroidal transformers be spread around all of the core in the manner shown in Fig. 70B. that is,k the primary and secondary windings should each be spread around most of the core. This is a proper method when winding conventional broadband transformers. However, it is not recommended when narrow-band transformers are being built. It is better to place the low-impedance winding (L1 of Fig. 70D) at the cold or grounded end of L2 on the core.

This is shown in the pictorial and schematic format Fig. 70D. The windings are placed on the core in the same rotational sense, and L1 is wounded over L2 at the grounded end of L2. The purpose of this winding method is to discourage unwanted capacitive coupling between the windings, which aids in the reduction of spurious energy (harmonics, and so on) that might be present in the circuit where the transformer is used.

In-circuit that have a substantial amount of voltage present in the transformer windings, it is good practice to use a layer of insulating material between the toroid core and the first winding. Alternatively, the wire itself can have high dielectric insulation, such as Teflon. This procedure prevents arcing between the winding and the core. Similarly, a layer of insulating tape (3-M glass tape, Mylar, or Teflon) can be placed between the primary and secondary windings of the toroidal transformer (Fig. 70D). Normally these precautions are not necessary at impedance levels under a few hundred ohms for RF power levels below 100 watts.

Once the inductor or transformer is wound and tested for proper performance, a coating or two of high-dielectric cement should be applied to the windings of the toroid. This protects the wire insulation from abrasion, holds the turns in place, and seals the assembly against moisture and dirt. Polystyrene Q Dope is excellent for the purpose.

The general guidelines given for toroidal components can be applied to pot cores and rods when they are used as foundations for inductors or transformers. The important thing to remember is that all of the powdered-iron and ferrite core materials are brittle. They break easily under stress.

## Simple, sensitive metal detector

The metal detecting hobby is enjoying quite a boom at the moment and treasure hunters are not just after gold. The price of the precious metal has risen in recent months, at around \$1,600 an ounce ...

## BASIC CIRCUITRY of METAL DETECTION Part II

Before getting into the circuitry, we had better take a quick look at how the single-transistor detector system operates. I'm sure that at some time you've heard a whistle or tone while tuning your...

## BASIC CIRCUITRY of METAL DETECTION

Note by Colin Mitchell: The first part of this discussion is a very old article using US imperial measurements, by Charles D. Rakes. A table of wire gauges is provided at the end of the article. Th...

## DIY LASER Based Pulse Transmitter and Receiver

The circuit presented here transmits pulses wirelessly to long distance (more than 20 meter) using keychain LASER (readily available in market). A transmitter generates continuous pulses that are f...

#### Get daily update

As the fastest growing demand of circuit and wiring diagram for automotive and electronics on internet based on different uses such as electronic hobbyists, students, technicians and engineers than we decided to provide free circuit and wiring diagram base on your needed.

To find circuit and wiring diagram now a day its easy. E-learning through internet as a right place to search an exact circuit and wiring diagram of your choice and it's much fun and knowledgable. On internet you will find thousands of electronic circuit diagrams some are very good designed and some are not. So you have to modify them to make them according to your needs but some circuits are ready to make and require no changes.

There are many categories of circuit and wiring diagrams like automotive, audio circuits, radio & RF circuits, power supply circuits, light circuits, telephone circuits, timer circuits, battery charger circuits etc. There are many types of circuit and wiring diagrams some are very easy to build and some are very complicated, some are so small and some contain huge list of parts.

We provides free best quality and good designed schematic diagrams our diagrams are free to use for all electronic hobbyists, students, technicians and engineers. We also provides a full educational system to students new to electronics. If you are new to electronics you are a student or a electronic hobbyist and want to increase your knowledge in electronics or want to understand electronics in a very easy way so this is the right place for you we provide electronics beginner guide tutorials to easily understand complicated electronic theory. Our mission is to help students and professionals in their field.