Digitimer does now offer a range of Neurodiagnostic accessories to be used with our stimulators and amplifiers. We appreciate that we cannot include all types of electrode, so If you experience difficulty obtaining electrodes of the correct specifications, we would be glad to help.

Of course we do. Digitimer manufactured several devices suitable for this. Certain configurations of the NeuroLog system can be used to generate quite complex trigger pulse protocols compatible with the trigger input of the DS7A/AH. However, our battery powered DG2A Train/Delay Generator complements the DS7A/AH by providing a continuous burst of trigger pulses with control over frequency.

The maximum output of the DS7A is 100mA while that of the DS7AH is 1A (with reduced output widths). We find that for the majority of applications, the DS7A is perfectly suitable, however, the main exception is where the human quadriceps muscle is being directly stimulated. In this particular case, we would recommend the higher output of the DS7AH.

So I think the problem you are having relates to the type of control signal you are giving the DS7A. The DS7A does not have any built in repetitive trigger facility i.e you cannot for instance set it to 50Hz and then “gate” it to be on for the duration of a TTL high command. Instead you have to supply one trigger pulse for each stimulus pulse, so if you want to deliver a train of ten stimuli at 50Hz, you will have to send 10 TTL compatible pulses at that required frequency. The DS7A is triggered by the rising/+ve (or with internal jumper modification the falling/–ve) going edge of a 3V to 5V TTL compatible rectangular pulse and this pulse must be at least 5µs in duration. So, in order to program repetitive stimulation you will need to deliver a series of such pulses via the trigger input. Should you not have this capability, we do have a simple battery powered device that can be gated on and off with a TTL high/low command. We can provide more details on this DG2A Train/Delay Generator, should you require it.

Axelgaard electrodes are pre-wired with a short pig-tail terminating in a 2mm socket. Digitimer typically uses 1.5mm DIN42802 connectors for our products, so in order to interface these electrodes with a DS7A, DS7AH, DS7R, DS5 or DS8R, you would need one of our D185-HB4 output cables (various lengths) as well as a pair of DS7A-M338 adaptors (30cm or 90cm) which convert from 1.5mm DIN42802 to a 2mm pin.

Our stimulators are not classed as MRI safe, as all of them contain ferrous materials which means they cannot be used within a magnetic field. However, as long as they are located beyond the reach of magnetic field or in the scanner control room they may be used. It is important that MRI compatible electrodes and cables are used within the scanner room.

The DS7A and DS7AH are not supplied with output plugs, however we do provide them as optional accessories. The part code for a pair (one red, one black) is D185-OC1.

The DS7A/AH triggers on the +ve edge of a standard TTL compatible logic pulse (+3V to +15V) of at least 5µs duration.

The higher output DS7AH has a limiting feature that for safety reasons prevents use of these wider pulse durations. Although your stimulator has DS7A on the front panel, please check the serial number label on the back of the unit, as I think you will find it indicates that it is a DS7AH.

Yes, it is possible to do this and the method has been summarized in an application note.