making a high-current switching relay

[faisal1]

i got my project idea from science buddies, it's called "create your own spark" it's link is: https://www.sciencebuddies.org/science- ... p027.shtml

but now, after 1-month they have posted a note that the high current switching relay they advised to build and use can't work for this design, so please tell me if i need to change my design, or if there is a way to make a switching relay.

this is what they said "someone who is extremely knowledgeable and comfortable building a neef vibrator from scratch could come up with a working design." so please help me

[Louise]

I believe the bizarrelabs link has an alternate design. You could start there for some design ideas.


Louise

[deleted-71827]

Hi!
Again, as you know, the original design of the project was based on a certain part which is currently unavailable right now. I would suggest you find a local expert who knows about electronics to help you with this project, since there are many advanced concepts involved. If not, you can check out this link-
http://mayank.gupta.googlepages.com/Cre ... nSpark.pdf
Hope this helps, good luck!

[Louise]

i got my project idea from science buddies, it's called "create your own spark" it's link is: https://www.sciencebuddies.org/science- ... p027.shtml

but now, after 1-month they have posted a note that the high current switching relay they advised to build and use can't work for this design, so please tell me if i need to change my design, or if there is a way to make a switching relay.

this is what they said "someone who is extremely knowledgeable and comfortable building a neef vibrator from scratch could come up with a working design." so please help me

One of our other experts has a suggestion:

Radio Shack Model: 275-218 | Catalog #: 275-218 12 VDC/10A DPDT Plug-In Relay can be utilized in a "Relay Chatter" circuit (slightly more involved than the original circuit) using a second 6v battery.

Instead of using the iron core / carriage bolt or steel rebar to open (note: contacts NOW shown incorrectly both electrically and magnetically) the contacts, a second battery and current path is used with the 12VDC coil in the 275-218 relay itself!

The diagram should show the use of Normally Closed (NC) electrical contacts and it should be shown oriented away from the electro-magnet (aka. the carriage bolt wrapped with the primary coil).

1) Wire the positive (red / +) terminal of the second battery to the negative (black / -) terminal of the battery shown in the original circuit. This point between the two batteries should be one end of the primary coil as well.

2) Wire the negative (black / -) terminal of the second battery to one of the relay coil connections on the relay.

Wire the other relay coil connection to the normally open momentary contact switch that is NOT connected to the original battery. This point should also connect to the capacitor and the Normally Closed (NC) relay contact.

The following connections should be similar to the original circuit:
3) One contact of the normally open momentary switch should be connected ONLY to the original positive (red / +) battery contact.
3) The Capacitor should be wired between the NC and common relay contacts.
4) The primiary coil should be wired between the common relay contact and the negative (black / -) connection of the original battery.

Circuit current flow description:
When the momentary switch is depressed, current from one battery flows through the primary coil. At the same time, current flows through both batteries and the relay coil which causes the normally closed relay contact to open.

When the relay contact opens, current stops flowing through both the primary coil and the relay coil. This causes the relay contact to close and the cycle repeats (relay "chatters" as long as the momentary contact switch is closed.

Likely circuit design issues:
If the resistance of the primary coil is too low with respect to its inductance, the original battery may not be able to supply enough power to "pull in" or open the relay contacts. Trouble shooting this issue can be done by disconnecting one end of the primary coil. If the relay chatters without the primary coil in the circuit and fails to do anything with the primary coil in the circuit, one of several solutions should be tried:

a) Use 24 AWG or smaller diameter wire for the primary coil
b) Add a 6 to 10 ohm 10 watt resistor in series with the primary coil.
c) Use a third 6v battery and separate the current paths. Disconnect the primary coil from the junction of the two batteries and wire the positive (red / +) connection of the third 6v battery to the positive (red / +) connection of the original battery connected to the momentary switch contact. Connecte the negative (black / -) connection of the third battery ONLY to one end of the primary coil and nothing else.

Note: All of the above variations can be used by themselves or combined with any of the other variations.

Note: Without modifications a+b in place, the useful life of the battery supplying power to the coil is greatly reduced!

Note: Investigators have tried to use a "single" turn primary and have had coupling issues. The magnetic coupling and impedance issues with "lead dressing" to prevent a significant reduction of coupling factors is quite an art and can't be calculated accurately. The use of an extra half turn so the leads come off in parallel (e.g. the same direction) is recommend. Unfortunately, this means more turns on the secondary are required; however, the calculations tend to be straight forward and the effects on coupling variation are reduced.

This is different from the bizarrelabs suggestions, which doesn't use any radio shack parts. (I think the sciencebuddies link says these instructions are from the 1950s, so I don't know how many 'radio shacks' there were back then!)

Anyway, as the project description says, this is a pretty advanced project and difficult even for an expert. There will be trial and error to build this.

Louise