Need circuit design help with model torpedo launcher

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
The IC1 555-timer comes from different manufacturers in different packages. I am going to select SOIC-8 package.
Don't worry about the dealer for now. They are readily available.

LMC555CMX
TLC555CDR
Thank You again for your time and help.
Question, will the circuit board have the same part location numbers as the schematic?
 

MrChips

Joined Oct 2, 2009
34,920
Thank You again for your time and help.
Question, will the circuit board have the same part location numbers as the schematic?
Component identifiers, C1, R2, etc. do not change and have nothing to do with their physical location.
The physical location of the component on the board could differ from the original layout. The correct location of the component will be shown in an updated layout.

When an order is placed with a PCB house to make a printed circuit board, the component placements are predefined and will not change. The PCB itself will have an outline painted on the PCB to show where all the components belong.

If I make a board for you, there will be no markings on the board. Components are placed straddling two gaps. Hence there is a lot of flexibility to place resistors and capacitors to span the gaps.

In this layout, for example, D1 and C4 span a gap. You are free to place D1 and C4 anywhere along this gap.


1767496077826.png
 

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
Component identifiers, C1, R2, etc. do not change and have nothing to do with their physical location.
The physical location of the component on the board could differ from the original layout. The correct location of the component will be shown in an updated layout.

When an order is placed with a PCB house to make a printed circuit board, the component placements are predefined and will not change. The PCB itself will have an outline painted on the PCB to show where all the components belong.

If I make a board for you, there will be no markings on the board. Components are placed straddling two gaps. Hence there is a lot of flexibility to place resistors and capacitors to span the gaps.

In this layout, for example, D1 and C4 span a gap. You are free to place D1 and C4 anywhere along this gap.


View attachment 361576
Sorry to ask this with ALL you have done here for me. Where is the circuit board terminals for the Magnetic Reed Switch? My eyes are the best later in the evenings so please excuse me if I don`t see it. Also, memory is a little poor so If I forget, Thank You ALL for your Time / Help with this again.
 

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
I can put the Reed switch in line with the battery.
Question for Mr.Chips, what would you charge me to make 12 of the circuit boards BUT I need them to be Max. 15mm wide, double sided would be Great, if possible the length upto you as long as it does NOT go too long for internal Cylinder space. Please let me know. Thanks
 

MrChips

Joined Oct 2, 2009
34,920
If I were to charge you, for it to be worth the effort, I would have to charge my professional rates. You don't want to know my professional rates!

Before sending this out to a PCB shop, I would recommend that you test out a prototype first. Which means sourcing all the components. The usual industrial suppliers that can be trusted are Digikey, Mouser and Newark.

You need to purchase the major components:
IC1 LMC555
HS1 AH182WG-7
M1 AO3400
VR1 1M trimpot

(I still have to check the availability, prices, and footprints of these components.)

I have SMD resistors and capacitors on hand. I do not have LMC555 in SMD SOIC-8 package.
I do have LMC555 in DIP-8 package which I would use since this allows me space to do the etching. A preliminary estimate indicates that the board size will be 15 x 30 mm, single sided. I can assemble one board for testing. You can have as many bare boards as you need if it meets your requirements.

As already stated, I do not charge for simple jobs. I do this for free as a contribution to All About Circuits community.
 

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
If I were to charge you, for it to be worth the effort, I would have to charge my professional rates. You don't want to know my professional rates!

Before sending this out to a PCB shop, I would recommend that you test out a prototype first. Which means sourcing all the components. The usual industrial suppliers that can be trusted are Digikey, Mouser and Newark.

You need to purchase the major components:
IC1 LMC555
HS1 AH182WG-7
M1 AO3400
VR1 1M trimpot

(I still have to check the availability, prices, and footprints of these components.)

I have SMD resistors and capacitors on hand. I do not have LMC555 in SMD SOIC-8 package.
I do have LMC555 in DIP-8 package which I would use since this allows me space to do the etching. A preliminary estimate indicates that the board size will be 15 x 30 mm, single sided. I can assemble one board for testing. You can have as many bare boards as you need if it meets your requirements.

As already stated, I do not charge for simple jobs. I do this for free as a contribution to All About Circuits community.
Wow that is Incredible News. Thank You. I'm off to ebay to go part shopping. Can I ask you what: HS1 (Motor)? If that is, their on the way, China. The rest I am getting through ebay.
If your confident in your circuit will do from my original post Then I defer to your Experience.

Just in Case circuit boards for sure. Can I get the one you wanted to test with the parts on it? I will use that one as a Master.

IF ALL works out from your end. Can I ask for some extra boards? No parts on them.

Also I need to pay you for at least Postage, I`m in Canada.

Thank You for your Help.
George
 

MrChips

Joined Oct 2, 2009
34,920
HS1 is a magnet sensor AH182WG-7 specified by the creator of the design @sghioto.
Obviously, this is a specialize component in lieu of a magnetic reed switch and it is up for discussion and substitution.

We don't know the strength of the magnet you plan to use. We don't know what is an appropriate sensor to use for this application. This will require some trial & error testing.

The MOSFET M1 is also subject to substitution.

This is why breadboarding and prototyping is highly recommended.
 

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
HS1 is a magnet sensor AH182WG-7 specified by the creator of the design @sghioto.
Obviously, this is a specialize component in lieu of a magnetic reed switch and it is up for discussion and substitution.

We don't know the strength of the magnet you plan to use. We don't know what is an appropriate sensor to use for this application. This will require some trial & error testing.

The MOSFET M1 is also subject to substitution.

This is why breadboarding and prototyping is highly recommended.
I see, I was just planning on using a basic Reed switch, that way a ordinary earth magnet would be able to control the reed switch. As for the MOSFET Good point about testing. All I can say is the motor will be turning a plastic small propeller in water only dealing with the resistance of the water for a set time of running. I think, NOT knowing alot of the MOSFET specks, not too large of a capable MOSFET is needed?
 

MrChips

Joined Oct 2, 2009
34,920
I see, I was just planning on using a basic Reed switch, that way a ordinary earth magnet would be able to control the reed switch. As for the MOSFET Good point about testing. All I can say is the motor will be turning a plastic small propeller in water only dealing with the resistance of the water for a set time of running. I think, NOT knowing alot of the MOSFET specks, not too large of a capable MOSFET is needed?
How much current does the motor need?
 

sghioto

Joined Dec 31, 2017
8,643
If you go with a mechanical reed switch it would be a direct replacement for the AH182 without changing anything on the 555 circuit.
I believe the hall sensor is more sensitive as I have used the AH182 in several projects with good resolution.
 

MrChips

Joined Oct 2, 2009
34,920
My solution puts a NC magnetic reed switch in the power rail.
The switch is open when the magnet is beside it. I am using two 2N7000 MOSFETs instead of the LMC555. If the motor draws more than 200 mA we can upgrade the MOSFET.

(I think I will use a SPDT reed switch to discharge the timing capacitor.)

I will post the circuit schematics later.
 

MrChips

Joined Oct 2, 2009
34,920
Would highly recommend the AO3400 for Q2, it has an Rds of only 52 mΩ, at 2.5 volts Vgs compared to over 2 ohms for the 2N7000 at 4.5 Vgs.
I haven't played with MOSFETs recently except for higher current ones like IRLZ44 and STP75NF75, certainly not ones in SMD packages.
 

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
I think I would like to stick with the Circuit shown on Post # 42.. My reason is that the AO3400 can handle upto 4A. That is MORE than enough power needed to drive the D.C motor. That motor will have physical resistance turning a propeller in water and driving a torpedo through the water. The only change in the circuit would be Just using a Magnetic Reed switch - With external magnet near it, power is OFF all functions dead. Remove external magnet and circuit is powered and torpedo is running for set amount of time. To reset/turn off circui9t just reattach external magnet and start again to use it.
 

Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
If you go with a mechanical reed switch it would be a direct replacement for the AH182 without changing anything on the 555 circuit.
I believe the hall sensor is more sensitive as I have used the AH182 in several projects with good resolution.
Can`t find on ebay the AH182. Sorry Just found it on ebay. Now what is better to use Magnetic Reed Switch OR the AH182? Price is a factor, Reed switch glass tube with leeds, durability issue???
 
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Thread Starter

JureGeorge#1

Joined Dec 31, 2025
39
Also forgot to mention, ALL circuit board mounted parts I decided to go after are 0805 in size. Might be able to see the little things.
 
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