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Member postings for Dodgy Geezer

Here is a list of all the postings Dodgy Geezer has made in our forums. Click on a thread name to jump to the thread.

Thread: Automobile heater motors/wiper motors on boat
08/10/2017 10:01:02

Two comments - one of those motors is a 24v motor, and there is no indication of motor power, weight or speed on any of the specifications. Without these it is hard to offer more than generalities.

Thread: Billing Boats Lilla Dan
07/10/2017 18:27:37

Why not try asking Billing Boats? They have a full archive...

Thread: Website wobble
07/10/2017 18:26:47

There are lots of checking sites. Try this - **LINK**

Thread: Automobile heater motors/wiper motors on boat
07/10/2017 18:24:44
Posted by Malcolm Frary on 07/10/2017 10:06:59:
.........

At one time, it was possible to browse a scrapyard and select the goodies you wanted - nowadays, you need to know the make and model and year, if not the actual registration of the car you intend it for. Using a motor for any other purpose is a foreign concept, for the sellers, things like "technical specifications" are equally foreign. .......

At one time it was possible to obtain car parts from a breakers, or an abandoned car, for pence. And there were very few other places to buy a large purpose-built model motor - the few that were available like the big Taycols, were phenomenally expensive. That was when the advice to use a car heater motor, or a military surplus motor was offered.

Nowadays car breakers will assume that you are using the blower motor to replace a failed one in a car, and will charge a good fraction of a new item price, military surplus is hard to come by, and large model motors, which are designed for modelling purposes, are much more readily available. So the advice changes...

07/10/2017 08:45:53
Posted by Gary Mullens on 07/10/2017 01:39:19:

Are their any build threads with car heater motors? I have been reading articles on action electronics trying to educate myself on the setup. Now, I understand a single speed 2 wire motor will do but what about the 2 speed motor setup? Anyone care to share how the setup will work? The components etc? There has to be more info or threads on this. Right?
.......

Your question seems to me to suggest that you think there is just one kind of 'car heater motor'. This is not the case. Manufacturers may use a variety of motor types - for all I know some may be using brushless motors. Unless you specify a particular motor we can only talk about generalities.

In general, car heater motors use a resistor pack to provide speed variation. This is quite inefficient, and means dumping heat somewhere - usually this is done by mounting the resistor pack with fins inside the car ventilation system. So, to use this technique (if you want to) you would need to obtain the resistor pack as well as the motor, and add a cooling fan. Resistor pack failure is a common problem with these motors.

Car wiper motors frequently use a different speed control technique which you may also meet on heater motors - they have a third brush unit set at 120 deg rather than the 180 deg separation between the two normal running brushes. Because the 120 deg brush sees less back EMF it carries more current, and the motor runs faster.

No doubt there are other more obscure speed control techniques you may meet on some motors. If you want to educate yourself about small electric motor design I can recommend this book by Jim Cox in the Workshop Practice series: **LINK**

Thread: Air boat size
06/10/2017 20:49:19

If you are making one, this may be of interest - it describes a boat of 1:2 proportions... **LINK**

06/10/2017 17:56:14

I presume that you're talking about the length/beam ratio? Airboats seem to come in all sorts of different sizes - the short stubby ones are going to be most maneuverable, but for carrying passengers they can be made longer - the wiki shows one with about a 3:1 ratio - **LINK**

Thread: Midwest Products plans
02/10/2017 21:33:56

I run a website on which I put old boat plans that are no longer available from the original companies - with their permission, of course.

Most companies have been happy to provide this. MidWest are the only company I have approached who stated that although they have no facility for providing copies of their old plans to customers - whether for payment or not - they will not give me permission to put any up on the web....

Thread: Futaba Challenger 35MHz to 2.4GHz DSM conversion
29/09/2017 15:51:08

Fine for a 35Mhz set - but spare a thought for the submariners if you have a 40Mhz set. These are getting rare, and it would be a shame to lose one of the only radios they can use...

Thread: Matching crystals, and testing them...
28/09/2017 09:15:00
Posted by Chrissy J on 28/09/2017 02:46:02:

Thanks for your help. Sorry my first post was such a newbie question but I promise I won't ask many more!

No question is too 'newbie'. We all learn something from them. Before you asked, I was not aware that it might be a practice not to stamp a crystal with the actual frequency, but to put the transmission frequency on both and put 'Rx' on the one which was 455 less than the marked value! Don't stop asking such useful questions!

Superhetrodyning is a technique used to help process the weak incoming high-frequency signal. It works by mixing that signal with a slightly different frequency, which results in a resonant 'beat' at a much lower frequency - much like two out-of-sync motors produce a characteristic beat. No matter what the initial high frequency is, the lower 'beat' frequency (called the 'intermediate frequency' will stay the same with different pairs of crystals if the 'offset' between them is the same, which makes things easier to handle in the rest of the circuitry. So the frequency difference is small, but critical to the receiver operation....

27/09/2017 21:27:42
Posted by Chrissy J on 27/09/2017 17:13:08:

Hello everyone!

I have in my hot little hands, an eBay special: a 40Mhz 3-channel radio set, with four crystals, a gift from my partner. Through dint of close examination, I've found that two are marked 40.975 and the others 40.725.

Am I right in thinking that I need to use matching-numbered crystals, as I recall doing so with 27Mhz a long time (1988) ago?

.....

Um. You are correct that you need 'matching' crystals for the band you are working on. But I would usually expect the Tx and the Rx crystal to have a slight offset, due to something called the 'intermediate frequency'. That used to require a 455Hz difference in the old AM days (except for McGregor, who used 470!). That's why you can't swap a Tx and and Rx crystal, and why they are marked that way.

What is the kit you have got? And what is marked on the crystals? Incidentally, I don't expect there would be any damage caused by trying them out - if they don't work they just won't work. But if we can find out what the frequencies OUGHT to be we will be in a much better position...

This link might help... https://www.rcgroups.com/forums/showthread.php?808548-How-do-you-identify-modulation-mhz-and-frequency

P.S

Having looked at the other messages here, I see we are talking about a Hitec Ranger set. It looks like Hitec crystals are readily available, and, looking at the shops, I see that they seem to print the channel frequency on BOTH the crystals, rather than the actual frequency each works at. See here, for instance -  https://www.modelhelicopters.co.uk/electronics/crystals/hitec.html

That's a bit confusing if you are trying to follow first principles!  However, it seems likely that you have a pair of channel 975 and a pair of channel 725 crystals - now all you have to do is find out which one of each pair is the Tx and the Rx crystal, which you can do by trial and error. Unless there is another marking or some kind of indication...

Edited By Dodgy Geezer on 27/09/2017 21:46:06

Thread: Todays Boating
27/09/2017 11:50:12
Posted by Noel on 27/09/2017 10:52:22:

Thank you for the suggestions on simple plans. The Thames lighter looks simple enough for me to tackle - not got space for extensive scratch building at the moment.

......

Ah, Noel.... the EeZeBilts are designed to cost pocket-money prices, and be built on a dressing table (or, failing that, in your hands!). They are intended for young kids to be able to make in their bedrooms and not annoy Mum.

26/09/2017 12:38:20
Posted by Colin Bishop, Website Editor on 25/09/2017 18:15:45:

Noel,

As Dodgy suggests, it would be great to get the boys (with help) to build their own simple models. Satisfaction guaranteed and gets away from the 'must buy it' mindset.

Colin

I suspect that the practice of actually making your boats is coming to an end. It is going the same way as mending your car or rewiring your house - all things that the average DIY-er would have been able to do 50 years ago. But the increase in complexity, the extensive use of micro-electronics and software, and the plethora of regulation means that almost all jobs now have to be done by a professional qualified specialist who has access to specific purpose-designed tools.

25/09/2017 17:58:20
Posted by Noel on 25/09/2017 14:16:07:

I do wish you could get tugboats or something more serene for children that actually worked, it seems the only working ready-to-run models under £150 are crazy fast.

I haven't seen any other bargains on ebay to get myself a second tug and thus give both boys something sensible to play with... the one slow boat I do have just causes arguments.

.........................

Noel.

**LINK**

**LINK**

Thread: HMS Belfast
19/09/2017 21:31:53

Yes, quite easily. You would only use the BEC from one ESC, and disable the other by taking out the +ve (red) wire from the receiver plug. Contact the link I gave you above - they will explain it all...

Thread: Many thanks, Peter Grain! 'Mr Gee Dee' finally decides to retire at 87.
19/09/2017 14:23:07

As Lawrie White once remarked, unless your circumstances are unusual - like owning the premises outright and having a monopoly of the trade in a pretty big city - then there's no decent living to be made from the model trade. If there was then we'd all be doing it!

Dave M

I'm not sure that the model trade per se is shrinking - there are more manufacturers of radio control kit than there used to be in the 1960s - and certainly some Chinese are doing well out of it, but both the retail and manufacturing businesses are changing fundamentally, and the old system of high-street shops and labour-intensive manufacture is, I think, starting to disappear. We are looking at a social change similar to the arrival of the train, the motor-car or television.

Just as happened with those changes, some jobs and skills will be lost, and others will grow in their place. Established industries will fight a rear-guard action against the change, and then finally give in to it. Do you remember the ITV TV strike in 1961-62?

Thread: Can you guess what it is yet?
18/09/2017 13:41:18
.......

My contribution to this ethos is to recommend getting old cine cameras for a pound or two. The zoom motors and gearboxes are superbly made, and great for radar scanners, gun training etc. I say this tentativly, because I once mentioned this in an enquiry about what to buy for that job. I was shot down, the attitude being a special item should be bought. Hey ho.

.

Yes - there seems to be a general feeling that has been running through society for the last 20 years or so that there is a 'right' way to do things, which is the officially sanctioned and approved way that is published by an authoritative body, and that any individual who decides to do something on their own, or questions the 'approved' answer to any question is instantly suspect.

And if there IS no 'official guidance' on a topic, there is a clamour for some superior body to tell us what to do...

17/09/2017 19:08:27

Ah, Chas, you are getting too good for this! Unless you have been peeking at the Eezebilt plans?!

**LINK**

It's not actually a klaxon - but you're so close we'll give it to you. The TRITON plans suggest using the spout with the neck of the glue tube as a searchlight, adding a bit of clear plastic on the front and a dressmaking pin head as the bulb...

Here it is on the left. To my eyes it looks more like a lamp shade...

light.jpg

17/09/2017 13:34:41

A nice idea - but no. This is for a boat - and glue tubes aren't made of lead. Think about shapes....

17/09/2017 12:05:41

Well, this thread doesn't seem to have attracted much attention, so here is my last offering, It looks a bit vague - but the clue is that Keil Kraft had already proposed a use for old glue tubes on one of their EeZeBilt plans...

glue.jpg

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Make your own contribution to the Website

We welcome well written contributions from Website members on almost any aspect of Model Boating with a particular emphasis on practical hints, tips, experience and builds.

In order to maintain a consistent standard and format, all suggestions should first be sent to me by Personal Message for approval in principle. Only a very limited amount of time is available for editing contributions into a suitable format for placing on the website so it is important that the material is well presented, lucid and free from obvious spelling errors. I think it goes without saying that contributions should be illustrated by appropriate photos. I shall be happy to give advice on this.

The Member Contribution area offers space for short informative mini articles which would not normally find a place in Model Boats magazine. It is an opportunity for Website Members to freely share their  expertise and experience but I am afraid that virtue is its own reward as there is no budget to offer more material recompense!

I look forward to receiving your suggestions.

Colin Bishop - Website Editor